Is she in pain?
It's obviously still guesswork, but for a start, what do you feed her on? After pancreatitis you should have been given advice. So this bout of illness is different? What colour and consistency of poo is produced? Pancreatitis can cause damage that leads to EPI(exocrine pancreatic insufficiency)...greyish fatty stools with Mr Whippy consistency . I had a dog with this, and it is controllable with pork enzyme supplements. It is rare, and often missed by vets.
If there is pain, blood, the runs etc there should be treatment to help this. Harmless Slippery elm powder, from Holland&Barrat etc is very helpful for a week, giving a quarter of a Teasp. mixed with a bit of water in the food. It smells like cinnamon, but is ideal because it makes a mucous lining on the gut wall, which protects it from acids, allowing it to heal. Humans use it. If the vet could be sure of IBD, they would have prescribed anti-inflammatories, eg a steroid.
Allergies are a huge area, so I would want to know what you use now, especially after the pancreatitis. Hydrolized food is a temporary fix, the food is highly processed to obliterate the protein markers. It is very very bland, and contains a lot of rice. Prescription only.
Do pm me if you want to.