I definitely agree with what Elise says about cerenia with regards to both frequency and tapering too soon. Likewise, any time I tried to taper Trix too soon, she started vomiting clear fluid again. She was on cerenia every day for awhile (I can't remember how long), and I've been holding her steady at every other day since about May (in large part that is now due to her CKD and not p-titis). It is easier to stay ahead of the nausea and pain than it is to catch up once it kicks in.
With the nausea and pain under control, she should willingly eat at least something, but with Trix, her eating habits did change to eating several small meals, rather than one large meal - this habit has stuck with her, even though the p-titis is now resolved. It took me awhile to adjust my thinking to that change. I've also heard that when dealing with p-titis, they do better with several small meals as opposed to one large meal because it is less taxing on the pancreas. So don't panic if she doesn't eat everything at once - just offer it to her again in an hour or two.
When you syringe fed Blackie, did you puree the food? That does make it go a lot more smoothly...even the smoothest of canned foods has chunks that can clog the syringe.
I'm sure you know this, too, but when syringing water, you want to go slowly, and go from the side of her mouth. You want to be sure she doesn't aspirate any of the water.
Continuing to send prayers....
