Hi,
An armpit lump is usually a lymph node and can be caused due to infective conditions usuaully and maybe malignant in rare cases. It can be caused due to shaving , use of a new deodarant or waxing. You need to get a clinical evaluation done by a physician to get a confirmed diagnosis. You should try some OTC painkillers, continue with the warm compressus and avoid waxing / shaving for a few days. If it still persists a clinical evaluation becomes necessary. Goodluck.
Hi,
Lump under your arm which is getting sore and tender suggests that there is some inflammatory response is happening at the site.
Inflammatory response could be to infection.
I think you should continue with warm compression, but you also need to start antibiotics and NSAID'S.
I think you need to consult with your PCP, start on antibiotics and decide regarding further course of action.
Hope this helps.
Bye.