Oof, wow. I had something like that before, @Miss_M. Only, it was when I used the monkey bars at my old playground without stop.
Anyways, I think picking it was about the worst thing to do. It opens up the skin allowing germs and other bacteria to get in and infect the vulnerable areas, but it's kind of too late for that now...
Whenever I have something like that, I make sure to treat it with some type of disinfectant. Take a look at it, if it's oozing a lot, wash what you can off (but DON'T try to dig anything out if you can't), then treat it with some medicine for that. (I'm not a medical expert or expert at anything about this, but I suggest you ask your mom to, if you don't have medicine for it ALREADY, to take you to a pharmacy to get something for it.)
Whatever happens, it's important to make sure it stays uninfected from other things that'll make it a whole lot worse.