As I think I've mentioned to you before, I had a nearly identical experience with one of my dogs when Victor's forumla changed. I actually didn't even know they had changed it until Grace started shedding SO BAD and I thought I might need to switch foods, so I looked at the ingredients to try to find something comparable and noticed Chewy was listing both the old and new formulas. The newer one seems to be far lower quality. I mention this because there's no way it was the placebo effect in my case because I noticed the random excessive shedding before I knew about the formula change.
Anyways, I know you can't do raw, but the first thing that popped into my head to maybe try was green tripe. I know Tripett has a canned Green Tripe dog food. I was having similar problems with my old girl. She would have occasional really bad diarrhea in the middle of the night and other than that had okay poops, but it was just never...right. Always a little off. I started giving her 6oz of green tripe every night with her dinner and it really seems to have done the trick. It's loaded with good stuff for the gut. The Tripett is a little pricey, but may be worth trying.
How long is he on the foods before you switch? Maybe give each food a little longer to see if he adjusts.
The only other thing I can think of is to feed him a little less. If I recall correctly his weight has been a little bit of a concern (as in being too lean) but it might be worth trying and see if things tighten up.
Anyways, I know you can't do raw, but the first thing that popped into my head to maybe try was green tripe. I know Tripett has a canned Green Tripe dog food. I was having similar problems with my old girl. She would have occasional really bad diarrhea in the middle of the night and other than that had okay poops, but it was just never...right. Always a little off. I started giving her 6oz of green tripe every night with her dinner and it really seems to have done the trick. It's loaded with good stuff for the gut. The Tripett is a little pricey, but may be worth trying.
How long is he on the foods before you switch? Maybe give each food a little longer to see if he adjusts.
The only other thing I can think of is to feed him a little less. If I recall correctly his weight has been a little bit of a concern (as in being too lean) but it might be worth trying and see if things tighten up.