Hi not really sure what to do here but 3 days ago I woke up with a lump under my armpit in the inside which was probably just a big bigger than a grape and didn't feel that hard. It was really sore to touch and stayed that way for 2 days. Today however it seems to have completely gone and there is no pain.

i have tried looking for an explanation online but can't find much. I don't know if it's worth going to the doctors.

would be grateful if anyone had any advice/knowledge on this, thank you x