facial swelling

I am 31 years old and have never had acne. I have the occasional zit around that time of the month, but other than that I have clear skin. About a month ago, I got a bump on my forhead that caused my forehead, bridge of my nose and corners of my eyes to swell to the point you couldn't recognize me. I went to the dermatoligist, which I have never done before and he gave me a shot in my forehead and some antibiotics. It didn't help, my face was even more swollen the next morning.  It finally went away on its own, but left a long knot on my forhead. 2 days ago, I had a little pimple come up on my cheek and it has now started swelling the same way. What is going on?? and what can I do to make it go away?? The zit is no big deal, but the swelling is disfiguring!