Can long term use of previcid/prilosec cause digestive issues, lower lft abdomen pain small/narrow stool, constipation, floating stool?

More info needed: Thanks for your question! Prilosec's main mechanism of action is to decrease acid production. Some of the more serious complications include a form of infectious diarrhea, known as C. diff (which is not very subtle). I suspect it's not the medication, but you could always try holding it for a few days and see if it helps your symptoms. Hope you feel better!