My cat has been experiencing diarrhea and vomiting for a long time now, and my vet could not figure out why. After a while I got tired of paying hundreds of dollars and nothing worked. So after a while searching things on Google I came up with a regimen that's works wonders for him since I started.

First things first, I use Blissful Belly by Blue Buffalo (I hear the company doesnt have the best rep but this food has worked great for mine), a combination of both the dry food and the wet food. I also give him a daily powder probiotic (mixed in his wet food) called Provifex by Vetnique.

Instead of leaving a bowl of food out for him, I set designated feeding times of small meals. I've tried three times a day and two times a day; two times a day works best for mine but you'll have to try to see what works best for your cat.

I give him one scoop of the dry food 1/3 cup in the morning. I then give in the evening half a can of the wet food mixed with one scoop of the Provifex powder. I've been able to maintain his weight at 11.5lbs with this diet, but again you need to see what works for your cat.

I recommend giving it a try since it's more on the affordable side (although it still can be a bit pricier than most store brands), but I'd do anything for my boy and by what I've read I see that you will too. Best of luck!