I have a 6month english mastiff who developed a bacteria about a month and half ago. It was treated and ever since then he has still had VERY runny bowl movements and vomitting. We have had Barium pass through and XRays done and everything looks great. We had another fecal done yesterday and it looked fine as well. He has no appetite and was throwing up yesterday too. The vet gave him a couple of injections to help with that and he is on meds. Any suggestions??? We are going on almost 2 months of this!!!
Was he treated with antibiotics? I would ask the vet about maybe using a probiotic to restore the healthy bacteria in his digestive system. Sometimes the drugs that cure one thing, mess up something else. Like when women take an antibiotic for a sinus infection it can cause a yeast infection. It kills the good bacteria too. There is a product called Bene-Bac that I had to use for that problem with one of my cats but I would definately ask the vet before you give him anything.
You can also try some pumkin with the probiotic. My girls get runny stool ever once in a while from eating stuff outside (mainly cat poo). I just give them some yogurt and pumkin mixed together. It usually clears things right up. You want to make sure there are no spices in the pumkin, just regular canned, or this time a year, I buy several cheap ones and freeze it.