Hello,
I cannot confirm anything without examination but it can be a cold sore or a boil.
Cold sores are caused by a virus and are extremely contagious. The only way of ruling it out is by getting yourself tested for herpes. Laboratory tests include: culture of the virus, direct fluorescent antibody (DFA) studies to detect virus, skin biopsy, and polymerase chain reaction (PCR) to test for presence of viral DNA. I sincerely advise you to consult a dermatologist and get it ruled out.
Hope it helps.Take care and pls do keep me posted on how you are doing or if you have any additional doubts.Kind regards.