Soreness under armpit

I have a small bump (not a pimple) that's really sore under my armpit that I get from time to time (every 3-4 months). I sometimes get this type of bump && soreness in the vaginal area too. It's usually bigger like a knot though. Other than pain medicine what are other things that i can do or use && what exactly is it?

[Dr_Aparna]

Hi,
This could be folliculitis, which is the inflammation of one or more hair follicles.Folliculitis starts when hair follicles are damaged by friction from clothing, blockage of the follicle.
In most cases of folliculitis, the damaged follicles are then infected with the bacteria Staphylococcus (staph).
Topical antibiotics such as mupirocin ointment can be applied to the affected area.
ref:http://en.wikipedia.org/wiki/Folliculitis