My Rag doll

I have a Ragdoll kitty 6 months old 4 the last 5 weeks he has been vomiting up his food once a week I waited because I thought it was a hair ball .But then noticed he was not playing , Took him to the vet, Dr. took xrays and blood work ,Told me his stomach was irritated .Put him on Hills D/D in 1 week again he vomited .It's been mostly food but on occasion just brown fluid. I have had  him on Instinct boost dry, and Primal Raw beef and salmon .Any ideas whats  going on? he is not eating much now but I think he doesn't like the D/D dry I'm concerned I got him from a reputable breeder.

Sounds like maybe the food has been irritating his tummy.  Did you recently switch foods prior to the Instinct or has he been on that forever?  Also, some kitties have a very difficult time with fish foods.  You might want to try a turkey or chicken food and see if that helps.

Has your kitty started the spring shedding?  I know it's a bit early but some kitties start around this time of year.  I have seen several Ragdolls here that have issues during shedding season because of the volume of hair they are swallowing.  Some people take their Ragdolls to a groomer for a lion cut early each spring to avoid the digestive issues that shedding season brings.

Is your cat having other symptoms? Fever or anything?