cat won't eat much but is hungry. what to do?

I have a cat who vomited his meals for a couple of days last week and then stopped vomiting but started acting hungry and only nibbled maybe 1oz at most of his regular 5.5 oz wet food meals 2x daily. What to do now that almost a week of this has gone by?
He is at least 12 yrs old. His breed is purebred Ragdoll. He used to b an
overeater and reached 21 pounds at one point. Two years ago he suddenly became gravely ill w what would b diagnosed as feline pancreatitis and diabetic ketoacidosis. After a three day hospitalization and $2000+ treatment which completely traumatized him(he sent a vet tech to the hospital after one too many needles) he recovered at home. For a year he had insulin injections which he tolerated well and was switched to wet food. His weight dropped to 15 lbs while hospitalized but climbed back to 19 during recovery and that is where he is today. One year ago his blood glucose draw indicated normal levels and the vet declared him to b in remission. He has done well on two cans of Friskies 5.5 oz each daily. At a recent vet exam he freaked out (hates vets now!) so we decided not to do blood glucose test as it would have been abnormally high due to his stress. Naturally I worry he is having another attack of pancreatitis and/or diabetic ketoacidosis. The vet says his teeth r good. His behavior is otherwise normal altho there is little urine or feces in the litterbox. He is active and does not seem to b losing weight nor does he seem dehydrated. I would take him to a vet but it would b a new vet as we have moved but I do not want to further traumatize him. He is not declawed and resists my efforts to groom and clip his nails and he will attack a vet tech if they do not heed his warning. I will try some chicken and rice or tuna and rice or maybe a fancy feast type of food. But I am concerned given his history about something more serious. He has not shut down completely and gone off to hide while sitting in the sphinx position as he did originally. should i try some pepcid?

Checking sugar is easy, if you know someone who is diabetic and will loan you their meter.  I don't remember the range for a cat, though your vet can tell you.  Put vaseline on the edge of the ear and use the lancet by hand, not by lancing device, on the little vein that runs along the edge of the ear.  The vaseline allows you to draw the blood with the strip and it won't hurt the cat when he cleans his ear.  That will give you a little more information on his health.

Something is obviously wrong with him, and if you don't figure out what, then you are going to probably lose him.   What about a mobile Vet?  Would he do better with an exam in your own home? 

Certainly you can try some Pepcid A/C (1/4 tab), but if it's pancreatitis, don't think the pepcid is going to help.  He may need some pain meds. 

I'm concerned with him eating so little that he may develop Hepatic Lipidosis along with whatever else is wrong with him.  Try to get him to eat anything...lots of different cat foods along with home cooked chicken and rice.

Thanks for good reminders and advice.
You reminded me of some things previous vet said. I gave him Sheba Perfect portions food -just one of the two small portions that come attached to each other. I will go get a meter or some strips and am going to call old vet to b reminded of her advice. And yes, I do need to think about the liver issues of cats losing weight too fast. He needs to lose weight (13-15 pounds ideal) but not by starving. I will weigh him too. His behavior is pretty normal but clearly he has an issue.