Bark splitting can be caused by herbicide damage, freezing temberatures, growth cracks, mechinacal failure from weight or weather, or lightning injury.
Discolored/sunken bark is often a sign of sunburn, check for cracked loose bark only on the southside of the trunk, if there only then it would be sunburn.

any storms that might have caused it? You don't have any sprinklers aimed at the trunk do you- this usually causes rotting/cracking/decay. How is your soil, is it well draining or does it have a lot of clay? Cherry trees also have a low-moderate salt tolerance.

My guess would be that something with weather- either sun, extreme temperatures, lightning etc. has had some effect on your tree, also, I don't think heavily spraying a trunk with fungicide is a good idea- you will most likely rot the tree if there is a cracked trunk and sitting moisture. You should have an arborist in your area come check it out.
Dying lower branches can be a sign of spring growth, if there is lots of new branches some will die off, it's only natural for the larger branches to outshade the younger, or they are simply the result of the cracked bark and your tree needs care.
Hope this helps, wish I could come over to check it out for you.
;) Danielle
Firegurl

thanks firegurl! I was going to spray the trunk this morning, heavily. I won't do it, and I will call my county agent to come and look at the tree. I appreciate your input.