Gaping Hole Underneath Armpit

Hi, I was wondering if anyone knows what this is.

What is it when I have a hole underneath my armpit. It does discharge some fluids, that do smell funky. I think I've had it for a week or two now. I don't believe its a pressure sore because It's not close to the bone. I do have several skin conditions, and one of the conditions have to do with the armpit. I believe its called hidradenitis suppurativa. Can that have to do anything about it?