Thanks for the query.
You might have developed a carbuncle
Usually it last for few days and disappear but may remain even longer
These are deep bacterial infections.
Persistant infection can be severe.
Treatment is with antibiotics but the choice of antibiotics should be based on culture and sensitivity tests.
Please get this test done and get yourself treated.
Please meet a dermatologist
for exact diagnosis.
Let me know if you have any other doubt.
you can ask a direct question to me on this forum, following the below link.
Wishing you a good health.