[bliss7373]

I do not think this is a blockage. First, his bowels are working - they obviously aren't blocked. Second, this has been going on for awhile. If he had a blockage, I would think he'd be in dire shape at this point, unless it were a very minor obstruction. I also agree that frequent vomiting, unsuccessful attempts to go potty, general nausea and distress are the signs of an obstruction.

Thought No. 1: Could he have developed an allergy to something in the Canidae? Maybe he's simply not eating it because he knows it's going to make him sick.

Thought No. 2: I wouldn't think a round of antibiotics will hurt him - this could also be a bacterial overgrowth in his gut, the antibiotics are likely designed to clear that up. Give the antibiotics with some yogurt, so they don't kill off the good bacteria too.

After the vet visit, I would fast him for a day to let his gut heal a bit, then feed him a bland diet for a few days. Don't give him the antibiotic on the day you fast him- wait till he's eating again. Once he's past this, if nothing conclusive is found, I'd consider switching to a different food.