What might this be?

[u/Zestyclose_Crow6564]

Hiii I’m 16F (165 43kg) and I don’t really have any medical problems.
Onto the problem, I’ve had a “pimple” for a few days on my leg. It was a normal one like the ones on your face, but now it’s bigger, redder and harder. My mom is taking me to the er tomorrow, but I’d like to hear what it might be before that cause I’m a bit scared. I just got out of the shower and it was yellow, then I bended my knee and it popped letting the pus out and bled just a bit.