I can only offer one suggestion, but I have no idea if it will work for you. Buy a super firm mattress for support and add a memory foam topper for softness covered by a quilted cotton mattress pad for coolness. You might need to replace the memory foam topper every couple of years, although I have had mine for four years and it's still going strong. It sounds like your husband has already ensured that the under support is firm and sturdy.

Fun, we did something similar.

I was always waking up with lower back aches so I bought a down filled mattress topper. It's like sleeping on a cloud except for when the little feathers pop out and stab you while you're sleeping, so I bought a quilted mattress pad to put over it. That works out well because now the down topper will stay clean. I have no clue how I would wash that. With that topper, I love my bed now.

another suggestion, are the slats supported too?
If the slats are sagging then so is the bed.

When we repainted our MBR, we moved the bed to the other end of the room, but didn't bother to put the supports under the slats. Felt like we were sleeping in a hole and after 2 nights, my back was killing me!

I hope you get some relief!

A number of suggestions...

you can put the plywood between the mattress and the box spring (I had a really bad mattress growing up and ended up putting it on the floor...that helped so much!)

you can buy an "egg crate" mattress pad that is used frequently in hospitals and is supposed to help with back aches

you can buy a sleep number bed (I've never tried them...don't know how loud the air compressors are) which is pumped up with air so should be more supportive and last longer. My mother used one once in a hotel on vacation and she said everyone on the tour said they slept better.

try sleeping on your side in the fetal position....knees up and together to straighten the hips and keep the low back relaxed...recommended by my chiropractor and it always works for me

Many good suggestions!

What olychick said. And plan to spend major money if necessary. Don't be penny wise pound foolish. Think of the purchase as a long-term invenstment in your physical health and mental/emotional well-being.

That's happened to me twice with my Beautyrest mattresses. The first one was replaced as defective but we had the same problem with the second. We're not large people so I thought it must be the mattress, but I never considered that it might be the bed. Extra slats wouldn't hurt.

So, we've been sleeping in craters for years and I keep meaning to buy a new mattress, but have been paralyzed with indecision :-). I went to Nordstroms yesterday and tried the Westin Heavenly mattress. I've slept on one before and it was wonderful and I'll probably buy one, but will wait for the 25% sale in July. Nordstroms returns anything, right?!

A mattress topper is a good idea, since this can be periodically replaced for a lot less $$ than a new mattress.

Thanks everyone!

Lynxe -- I spent major money the last time we bought mattress and box spring, so it really irritates me that the dang thing gave out after only a year or so.

Annie - I sometimes try to sleep on my side, but as soon as I'm actually asleep, I'm on my back... at least I avoid facial sleep wrinkles!

Pudger - the slats are supported, but just to verify, I think I'll ask my husband to get in bed, and then look under the bed.

Several of you suggested mattress toppers, but at least the ones I've tried in the past have not been helpful. But maybe on top of a really firm mattress, that would work.

Olychick -- I've not heard of a natural latex mattress -- I'll have to investigate - thanks.

So, we've been sleeping in craters for years and I keep meaning to buy a new mattress, but have been paralyzed with indecision :-)

Or maybe you just couldn't get out of that crater!

I have been told that the worst mattresses for "cratering" are pillowtops, and that it's better to buy a non pillowtop mattress and add an extra foam topper to get the same feel as a pillowtop. That way you can replace the topper only as it wears.

I bought a latex mattress a few years ago, and while we like it, I think that it might be a bit too firm. I had wanted to get a mattress from FloBeds, which sells latex mattresses that you can customize, but a local store had a really good deal on the latex mattress that I bought. I think that I need to add a softer latex topper to it.

I also found a lot of good information on the What's the Best Mattress forum.

My previous mattress definatley was causing me lower back pain, but it was obviously dipping in the middle. (queen size) and when I replaced the mattress, I did notice a difference. I again was noticing lower back pain after a couple years with my new mattress, but I believe it was from stress. I would go to bed using a heat pad on my back to help etc etc. I haven't noticed any back aches for quite a while now and I really do believe it was from stress...Just something to think about.

Have you contacted the manufacturer? I wonder if there could be any warranty for this.

Soft sided water bed. There is nothing better in my opinion!

I second a natural latex mattress. They are very heavy and need a lot of slats to support it, but shouldn't be put on an entirely flat surface (like a large piece of plywood) because it needs to breathe. We also met someone who had theirs for 30 years and it was still going strong.

Is anyone familiar with Saatva mattresses? I'm seriously considering one and wonder if that might work for you, too, mjlb.

Here is a link that might be useful: saatva

There is a lot of good information on the web that you should research before you spend more money. Most mattresses are going to feel good for the first few years.
Do consider the natural latex--not synthetic or blended. We have a Savvy Rest King. It is a latex foam that comes in three layers and three firmness levels that you put together yourself-very easy and you know what's really inside. Natural latex can be pricey, but lasts for years.

We are very happy with ours, but there are other good brands out there as well.

I have no connection/interest in Savvy Rest.

I recommend a Tempurpedic, memory foam (closed cell, not imitation foam) does not compress over time so it will never indent or sag. I tried out latex but as a side sleeper I need a softer bed that conforms to my hips and shoulder and the latex were all rock hard, I'd get hip pain. Spring mattresses just do not last, especially the new trend in pillow tops.