After reconstructive surgery, I have extreme pain when I relax bladder muscles?

Extreme pain when I relax muscles to urinate.

I’ve recently had reconstructive surgery done on my bladder and right ureter as a result of a cold knife cone gone wrong. All while I had my catheter in, there was still a lot of pain if I relaxed my muscles. I’ve recently had the catheter removed and when I go to urinate, there is a god awful pain that is intolerable. Is this common? I’m taking my pain meds just to be able to use it, but it’s not working.