I have a small pea-size lump on the back of my lower leg that comes and goes. Often I can t even feel it, but sometimes it appears, and when it does, it cause a burning, painful sensation in my lower leg. Then it goes away, especially if I walk around or elevate the leg for 15 minutes or so. What could this be? I am a 64 year old female in good health with no illnesses or issues.