<s>[INST] Hi i am a 14year old female....i had a bump on my left armpit for quite a while now, how long i cant remember. Todayi was rubbing my armpit and a black substance popped out of the bump....it looked like a mini raisin but with pit hair on it. As it popped out it left a hole/tunnel in my skin. Its quite disguting&im really worried [/INST] Hello! Thank you for the query. Most likely the lump is nothing more than a cyst caused by ingrown hair. The hair could be there for a long time growing constantly. As it has popped put, most likely nothing more needs to be done. Please have it under observation. If the hole will slowly get smaller, no need to do anything else. However, if this won't be getting better, you should consult dermatologist. Hope this will help. Regards </s>