I think you should get checked out.
A friend of mine had an emergency c/s & lost her baby 6 days later. I went over for the funeral & took her home with me for a few days. She couldn't walk any great distance, but she could walk. That was about 2 weeks after. I think you should still be a bit uncomfortable, but the tenderness you have just under your belly button doesn't sound right.
Haven't had one personally, so not an expert.

Hope I helped a bit. Wish I could help more. Sorry.