Lumps In Stomach

I wasn't sure where to put this exactly, so I stuck it in pre-op - mods if it needs to be moved, I apologize!

So last December I noticed several rock-hard (marble and ping pong ball sized) lumps beside and above my belly button. No pain, just lumps. Went to the doctor and ended up having first an ultrasound and then a ct scan. They didn't show ANYTHING. So the doctor surmised that they were lipomas.

Now one of them is hurting - so of course I think it's something horrible that will prevent me from having surgery. Has anyone had anything similar?

ETA: I should add that the lumps can ONLY be felt when I stand. They can't be found by myself or a doctor why lying down.