Sorry I can't help too much, but when i was a vet tech, (only a few years ago) there were a few dogs there w/ pancreatis, although none had any seizures from it. they did have other symptoms like diarreha.

Of course all the dogs were underweight. Our vet perscribed a medicine (i think the actula name was pancreatis enzyme or something w/ pancreatis in the name), it came only in powder form, in a brown plastic bottle w/ yellow lettering. Our vets perscribed that & a good quality food (not low fat, just regular good food). The medicine was ver expensive (about $100-$150
per bottle which for a larger dog would only last a month or so).

It takes a while for them to put on weight (months & some times more months) & they will almost always stay on the slim side, but not emiciated though. But the diarrhea would go away in a few weeks or so at the most.

Maybe get a second opinion, it can't hurt.
i wish you the best of luck