A lot of cats with pancreatitis do end up on metronidazole for loose stools or diarrhea. I would contact your vet and ask for a weeks supply of this. I hope that he is still eating as this is necessary for his recovery. The metronidazole should help his stools within a couple days. If he stops eating or is vomiting I would suggest a recheck by your veterinarian and a possible diet change to something hypoallergenic.
Please let me know if further assistance is needed.