Dear Doctor, Please, please help me find an answer to this problem with my 3 year old daughter. She was complaining couple weeks ago that her leg was hurting, mostly at night when sleeping. She even spent one night crying a lot from pain. I just kept massaging, didn t notice anything. Then last week my mom discovers that she has a bruise and a painful lump behind her left leg, under the knee joint , not behind the knee, a little under it , towards the outer edge of the leg. It is pretty hard and quarter size and bruises are getting colorful, all around it. I have no idea whether she hurt herself, or if it occurred out of nowhere, by itself. I will be so grateful for your answer, I ll keep you in my prayers. Thank you, Warmly , Nelli