Pulled muscle where rectum was?

Help! I am 5 years post op having my rectum removed and a permanent colostomy. The other day I was doing leg lifts when I felt something weird in my butt area. Fast forward 2 days later and I could hardly walk. It feels like something is in the area like a lump or a tear. I had a complete CT scan and it showed nothing. I had a urologist and gynecologist take a look to see if anything prolapsed and she found nothing. Meanwhile I’m couch bound and it sucks. Has anyone heard of this happening? Any thoughts would be appreciated, I don’t know who to see next about this.