Went of PPI's now have burning stools?

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I'm going for a pH test next week. My doc asked me to go off my PPI (Protonix) 10 days before the event. I'm on day 3 now of not being on Protonix and I've noticed that my stools are softer than they were while I was on the pill, plus they seem to burn some. (No blood or discomfort, other than a bit of burning.) Could this be due to the increased acid production since I'm off Protonix? Maybe the acid irritating the bowels, so stuff moves out faster? Also I've read that constipation is a possible side effect of PPIs. Maybe my stools are just returning to a normalish texture?

PS. I also have gallstones AND had a low score on the HIDA scan, plus I was shown as being borderline gastroparesis (though I think it's related to the gallbladder troubles). Doc wans to see whether I have too much or too little acid, because PPIs seem only to work for a very short time with me (6 months, at most). Don't know if this info is helpful, but thought I'd throw it out there.

Thanks