My weimaraner has a severe illness. He quits eating and has a bloody stool and blood in his urine, after a few days on cephalaxin, he begins eating again and within a few days is back to normal... seems to be fine for a few weeks and then it starts over again. The Vets(4 of them) have yet been able to diagnois the problem. This has been going on for the past year... any advice ?