I had a lipoma removed in July from the bottom of my left buttock. They thought it to be small because they could only see the top, but turned out to be the size of a large grapefruit. My wound opened and I had about 6-7 weeks healing time. Everything was good, but now I'm starting to feel pain when sitting like before, feels like I'm sitting on a rock. I can't feel any lump though like before, should I be concerned?