Hopefully, it was just a super fast, transient low in which case not a big deal

. And cue my occasional plug (& love) for Libre

!! You would be surprised by what we don’t catch— so much happens SO fast at times.....there are some interesting transient events day to day. It is fascinating. It certainly helped me calm down by seeing the more complete trend data

!!
I also wanted to mention that while I know you have been using a hard tummy to gauge pain, many times a hard belly in cats is actually due to an indigestion/gas issue. Given the fact that Butters continues to belch lends more evidence to something going on from a GI standpoint vs just pain from chronic pancreatitis. This is important because it helps with differential diagnosis (what else may be going on or actually may have caused the pancreatitis?) as well as with management based on a more specific diagnosis. Sometimes it takes time to figure it out as you trial diets, meds, repeat diagnostics.
You have changed the diet

, which hopefully, if there was or is any remaining intestinal inflammation as a result of a sensitivity to an ingredient &/or protein pre issue, it will resolve and help with the gas. You have also discontinued the Bupe which can interfere with motility to some extent (how much is different with every cat...some have no issue while others have some issues). You may want to try a slow feeder just to slow her down if you suspect she may be eating too fast and swallowing air in the process. That will help her some if she does tend to eat too fast

!
At some point, if the belching, probable gas continues (aka hard belly), as well as the need for gabapentin, it would be worth pursuing differential diagnosis. If there is an underlying intestinal issue, such as a motility disorder as just one example, (there are many different GI issues) there are some good treatment options available

. Ultimately, once you identify the cause, you nail the treatment(s) and the pain goes away

.