Just the other day I felt a lump at the back of
, right side. It seemed small, pimple-size, and so I didn't worry about it. However, it's been a few days and it seems to have gotten bigger. It's under the skin, doesn't cause much pain (generally painless, but sometimes if you press on it, it aches. Other times it randomly aches on its own), doesn't move, and seems hard (though I wouldn't describe it as rock hard). Does anyone have any idea what it could be?