My three year old yorkie is poorly.?

three weeks ago he started vomiting at least three times a day, and also regurgitating his food. he wasn't able to keep down any water either. i took him to the vets and was told he didn't have a temperature. but his anal glands were big and his stomach was tense. they prescribed him with pro-kolin and a solution to keep him hydrated, it didnt make him any better and when he had two stools with bloody mucus i took him to the emergency vets they then gave me more of the solution and also some zantac and antepsin. he seems alot better than he was but is still being sick on a daily basis. its a white foam and he seems to be choking/suffocating when he does so. its quite scary and i am very concerned. any advice? thanks.