Wake up with red, very painful bumps on leg every few days, always in the same area.

[RDeAngelo88]

A few weeks ago, I woke up in the morning with one singular whitehead-looking bump on my leg, surrounded by a larger red circle.  Nothing comes out when I try to squeeze it (bad, I know), but it's very painful to the touch, not itchy.  The pain will subside after a day or two, then the bump eventually went away.  Shortly after it went away, I woke up with another one, on the same leg and a few inches from the old one.  Same thing has repeated about 5 or six times now, always within the same maybe 5" area of my leg.  Anyone had any idea what this could be?  They aren't happening anywhere else, and again, are very painful but NOT itchy.