Hi there, I just noticed a lump on the back side of my 6 y.o. daughter s leg. It s just below the back side of the knee on the medial side. It s about an inch in diameter, it s moveable, painless without any redness or noticeable swelling. She s also ℅ fatigue a lot lately, but I m guessing that s related to the cough/cold she s had. I called our doctor s office and they said it s probably a cyst because there s no pain or swelling, but I know that serious problems often times don t have pain related to them.