Since he hasn't been well more than likely it's coming from lack of vitamins is you niacin powder flush free or time released because neither of them will help him. Mix it into his tube feeding so he gets it undiluted which is what happens when added into the water. Or go get Liquid B Complex and add it to his feeding. Or Poultry cell both are great for getting them back up after being sick.
Great to hear he is doing better though.
Great to hear he is doing better though.