Hi, I'm 24, 5 foot 4 and about 120 pounds. I am on antidepressants and the birth control Yasmine. For the past few weeks I noticed a very tiny, painless bump about four inches below my knee, on the side (lateral) that seems to be just underneath the skin. It is hard to the touch, doesn't seem to swell, does not seem to have pus in it, and is about the size of a seed (in an apple), so about 2-4 mm. What could this be?