Your post just brought to my mind,there is a product called,Prozyme,it helps with a lot of this problem.
There is one formulation for pets and then they make one for humans.
It's been years since I used it on my dog,when she was young she was so finicky I wanted to be sure she got the best nutrition with her food,this stuff helps aid digestion and vitamin efficiency.
Maybe it can be "googled",I'm sure they have a website. It's good stuff,in fact I am thinking of getting some for myself again.
Thanks for sparking my memory,even though I digressed.
Wish you improved health soon.

(((((((((((( Sky )))))))))))