Since you've tested for just about everything else, the thing that grabs my attention is the foam he ate.
The fact that he's still having problems suggests to me that he may have some of the foam wedged in his digestive tract.
My sister's Standard Schnauzer ate one of her son's small toys and was tested and treated for everything from worms to pancreatitis and she ended up having to have surgery to have this thing removed. They were able to see it in ultrasound. Don't think you can see foam this way, but I know it's one of the things we're very careful about keeping from our dogs because it can cause these problems if ingested.
Got my fingers crossed for you.
CJ |