The First Time This Happened I Had A Cyst On

The first time this happened I had a cyst on my leg, I popped it. Second time I had a pimple and I think I let it go but have a mark, the third time I had a smaller sized bruise with a red dot in the middle and now I have a red circle with a bruise in the middle and it hurts. This has all happened on my left lower leg. What is happening or what could this be?