Ok I’m gonna take a a shot at this one and hope this helps. Ol Roy is a no no when it comes to pits. Really want to feed only pet store available brands and all natural. I know you are probably saying yeah right it doesn’t have to be all natural and I thought the same way when I kept hearing of foods like that. I’m going to say and I don’t want to toot my own horn but I’m probably at least 98% sure that it is his food. I have learned this in my experience with my two pits. You name it they have it as far as allergies and some health probs go. I got my male pit Ace from the local (no kill) humane society. He had just turned 1yr old so he was pretty much the size he was going to be (wrong). He was so skinny so I asked them what he was eating and they were feeding him 6cups a day of science diet puppy and he wouldn’t gain a pound! He had been raised their so he was on the same diet until I got him. Right after adopting him I noticed his gas was OMG Horrible. It would literally run you out of the house. So by contract I had to take him to the vet and I was talking with her and she said it sounds like food allergies or IBS (irritable bowel syndrome) because he also had extremely loose stools and was frequently pooping. So I put him on Iams Proactive Lamb and Rice for sensitive stomachs and he gained 20bls and filled out and is at a perfect weight now. I know Iams isn’t a natural food and you can buy it anywhere but I was unaware of the others at first and natural dog foods can be extremely expensive. Then my female pit Kira started to get severe allergic reactions and her face would swell up and hives on her body. So the short of it is she has severe food allergies. She is now on Natural Balance Venison and Sweet Potato It is $50 for a 28lb bag versus $32 for a 44lb bag of Iams lamb and rice. But it saved her life and is worth every penny. I am switching Ace to that as soon as we finish up the Iams. So after telling you my exerpience I am say put him on a good all natural food and see what that does. Keep in mind you don’t want lots of grains and chicken meal those are just fillers. I know there are some holistic brands, taste of the wild, and natural balance are going to be your major brands to look for. Hope this helped and let me know how he does. Oh also when doing a food trial for allergies and what not it can take up to 6 weeks to see the difference in them.