I only have a minute, so here goes:
I would be assured that he's in pain! Generally, Pancreatitis means PAIN!
I suspect that many more cats have pain from pancreatitis than show this pain. I think it is best to just assume that pain is present and to attempt to use pain control if pancreatitis is suspected, especially acute pancreatitis. Unfortunately, the choice of appropriate pain relievers is smaller for cats than for dogs. It is possible to use fentanyl patches (Duragesic Rx), tramadol (if oral medications can be used), buprenorphine, constant rate intravenous infusion of ketamine or morphine (must be done carefully in cats) or butorphanol (Torbutrol, Torbugesic SA Rx). http://www.vetinfo.com/cpancrea.html
Just a head's up for you.....DON'T accept non-steroidal anti-inflammatory pain meds
- such as Metacam - (which are now being given out like candy). Cats cannot metabolize them and they are known to cause kidney damage. In my experience, the easiest to administer pain control is Buprenex (buprenorphine), dropped into the mouth, NOT swallowed, but absorbed through mouth tissue.