Thanks for writing in.
The condition you are describing looks like furancle i.e hair follicle inflammation
. Simple antibiotic cream like mupirocin
helps to cure it. But if you rub it then it will spread as it is an infection.
Keep wearing loose cotton cloths. Apply powder to take care of sweating. If it spreads more, consult dermatologist
to treat infection.
I hope I have answered your query.