I hear ya my friend! My cat has had nothing but issues. He is only 2 years old!
He was fed Iams Kitten food, dry for his first year, then one day out of nowhere he started seeping blood out of his Anus. Turns out he had an intolerance and his bowel couldn't process the food.
We switched to a grain free wet / dry mix. This time with Felidae Platinum, and some probiotic dry.
The lack of grains, and the fact that is was for senior cats made it much easier for him to digest. Then around 2 weeks ago, out of the blue he became lethargic, he was at deaths door, I took him to the vet and he had a Urinary Tract Blockage. In short $1200 later he is up and running again.
Once again, his food has been switched. Now he is on Vet Prescription Dry food, sprayed with water before eating. And Wellness grain free chicken food.
Its crazy how bad for cats cat food is! It makes me so mad! I have been to the vet multiple times for no reason other than my cat's reaction to his food!! And he has never been fed cheap crappy food!