Izzy went through the same thing. We tried all kids of different food including Blue, it did not settle with her well at all. (she's VERY picky).. At that point we went to Natural balance L.I.D..(one protien food and grain free) They had all sorts to chose from... She liked the bison & sweet potato and she also like the Venison & sweet potato... We gave her dry kibble and wet.. She loose stools went away
...
Then she turned her nose up to it
Would NOT even touch it... I finally decided to try Raw food... She loved it!!! She now eats Primal raw... she also get orijin dry kibble too... it's great food...
I would first take him to a vet to make sure everything is ok... Then switch him to a the L.I.D food
His tummy must be really sensitive... Good luck and keep us posted on how he's doing...