Two Weeks Ago I Had Lithotripsy For A 2cm Stone

two weeks ago I had lithotripsy for a 2cm stone in my ureter. The very first thing I noticed when I woke up from surgery was that my stomach was extremely bloated, very uncomfortable. I weighed myself before and after the procedure....after I had gained 5 lbs. My belly is still bloated and very uncomfortable, and feels very full all the time. What causes this?