I Just Went Off Tylenol 3 (back Pain) And Movantin,

I just went off Tylenol 3 (back pain) and movantin, a new med to stop option costipation. I'm off everything, but my stomach is extended and I feel like I have a 5 month pregnancy sized belly. I'm 60 and very active exercising every day. I had a full checkup in Jan. with blood screenings etc. I'm a female with low blood pressure and low cholesterol. Any idea? Thank you.