Dogs change as thay age and feeding habits do the same.

I do not allow any of my dogs people food. I don't eat dog food---they don't get people food.

Actually, that is not the reason. My dogs are dogs, if they ate the same food as I do it creates bad habits. First, eating from the table is a huge nono. Second, part of my pack leader protocol is for me to feed them. That reinforces my leadership.

Is your dog overweight at all? Getting people food(and all the flavorings/spices that are used) can create a preference for people food over dog food. That can cause the dog to change thier diet, which can cause the vomiting. Which may be a simple case of upset stomach.

I feed our big dog Pedigree---dry and canned mixed. The other dog has to have a lamb and rice diet---I use Purina dry and Pedigree canned(Chicken/lamb and rice).

The big dog often will not eat all of the serving when I add chicken canned---he just does not like it.

I only feed once a day---and seldom at the same time of day. Might be 4:20PM or it might be 9PM. There are several reasons for that. Pack leader ritual, the fact that dogs in the wild eat when they can, and my daily routine does not allow me to feed on a strict time schedule.

Add to all that the fact that older dogs often do not eat like they did as puppies. And, dogs need to anticipate feeding---not by barking/acting up, but just the fact that feeding time is special.

My two dogs will come and ask to be fed. Some times I feed them then. Usually, I make them wait---10 minutes to several hours. Then I say "Ok, feeding time." They run to their respective feeding areas and lie down, waiting until I get the bowls, mix the food, and set the bowl on the floor. Alpha dog first, he waits until I say "Ok" and then the other dog---same "Ok"

Then I leave. They eat, come into the office, living room, where ever after they finish and lie down. If they do not finish the amount---I put the dish up---for the next days feeding.

Your dog needs to eat more often. The bile is a result from an empty tummmy, My dog does the same thing. If I dont feed him a little every 4 hours, the bile will build up causing the stomach to become irritated and he will throw up. So just feed your dog a cup of food once every four hours, or give him a couple of slices of Natural Balance meat stick. That should fix the problem.
Try and stay away from dog foods like Pedigree which have high sugar contents and lots of filler in them. Dont switch food abruptly because it may make your dog sick. During the dog food recall I had to switch food and my dog got sick from eating even a high grade food.
My dog is free feeder as well. I give him Natural Balance meat sticks - which if he leaves in the container (he eats out of an old dog bed) the sticks turn to jerky and he will eat them dried out.
Here is an inexpensive but healthy dog food diet.
Go to Trader Joes and get yourself some canned dog food they are less than a dollar a can and the cans are huge. Go get a Natural Balance dog food stick, a case of Vita Bone dog cookies (get the Kennel pack at $12) Lucky's carrys them. If you belong to Costco go get some hamburger and some broiled chicken and a big bag of rice.
You can debone the chicken and freeze it, it is only $5 a chicken, you can split up the hamburger, brown it and freeze it as well. Boil up the rice (I cook 4 cups at once in the rice cooker and put it in a bowl in the fridge - I grab a couple of handfuls and add it to the chicken, hamburger and trader joes dog food add water until things start floating around) I always mix it up with my hand to make certain there are no wayward chicken bones in the mix...leave the meat sticks and the vitabone dog biscuits out for your dog to eat when he wants and offer him the dog food bowl with the Trader Joes dog food, chicken, rice and hamburger twice a day....
It breaks down like this:
Hamburger $20 a container - will last a month
Chicken $5 a chicken - one chicken de boned will last four day
Rice - a huge bag is $10 this will last you 6 months easily
Meat stick $9 will last about 2 to 3 weeks
vita bones - will last close to 4 to 6 months
Trader Joes dog food - one can lasts about 4 days
Total cost each month is about $100.00 your dog will eat better and eat less, and poop less because the food is higher grade. I live on a limited income and have been feeding my dog this mix for over 5 years now. Adding water to the bowl allows my dog to ingest a bit of fat and nutrients even tho he is not eating the actual meat of the chicken and beef. This keeps him from throwing up because the fatty soupy mix coats his tummy just enough.
I hope this helps and I hope you repost and let me know how things are going.

My dog was having this problem a couple of years ago. I put him on a grain-free diet and he does much better on that. Grains are hard for dogs to digest. Also, you could try some probiotic supplement or I just give mine a little plain, nonfat yogurt every morning to help their digestion. The one who was throwing up before is almost 15 now and doing great.

I'd look at the feeding schedule... spreading it out so he doesn't have empty tummy.

And I would look at changing the diet, grain free if you can.

And I would do a search on this forum for vomiting dogs. We've had lots of informative posts on this issue in the past.

Best of luck to your dog and his tummy.

My female labradoodle has always been one to spit up at random times. Like yours, its the yellow frothy bile and would often happen when she was running around playing.
I always had given her Nutro, the oatmeal formula for sensitive stomachs. She eats twice a day with snacks inbetween (doggie, not human).

Anyway, we discovered that she had bladder problems, crystals and blood in her urine. We switched her to Royal Canine SO formula and she has not spit up since. Its been about 2 months now and she is still just eating 2 times a day and has the same treats.

So, maybe there might be another problem that you may not be noticing. She did not show any other symptoms, not leaking or potty accidents, just occasionally I would find a spot of reddish color dry urine spot on her bedding. Not everyday, and not much but we treated with medicine 2x. It wasn't until we switched food and the crystals went away that she got better.