Why is my boil turning purple/blackish?

Fair warning- pictures aren’t pretty.

I typically get ingrown hairs/small cysts between my thighs because of shaving and my thighs. I got a boil on this same spot about two months ago. I didn’t pop it and I let it heal on it’s on. Even though I didn’t pop it, it still left a purple scar.

Two days ago I feel a little pain when I wake up and that boil reappeared except the boil and skin around it was pink/reddish. The pain is worse and it’s bigger now. It also has turned soooo dark.

Anybody else experienced this? Should I be concerned?