Wht Could Pinching Feeling In Lower Abdomen Post Childbirth Indicate?

I started to get a pinching feeling in my lower abdomen after the birth of my son.there was a small blood discharge when it first happened.its been almost 3 years.i still get the pain. Doctors can t find out why. I had 2 colonoscopy done, blood in stools test done, pelvic scan etc.im so worried!