Pain after heavy cycling. Could it be?

Hi, I am a cycling lover. I am suffering from a mild pain in the region starting from lower left abdomen to left side of my crouch since 1 year(this isn't regular and occurs occasionally when I'm cycling or exercising heavily). It first occured during my heavy cycling in last year. Initially it was paining alot and now it has reduced by 70-80%. I've no serious issues like Blood in Urine/Stools, no back pain, no swelling in the region, no vomiting only mild pain. I can even run fast as much as I can. However the pain appears only when I bicycle again and lasts for about 15-20 days. I've consulted many doctors they said it must be a muscle tear which might take a longer time to recover in my case as I'm heavy but not fat. What could it be?