Dear friend, welcome to HCM.
i see that it is persistent.
has it increased in size ?
is it soft or hard?
is it fixed or moves with fingers?
can yu post a photo of the lump here on the website, so that I can tell you more confidently?
it is better you see a general surgeon
to get evaluated. since there are many kinds swellings that can occur in the armpit, an in-person checkup is more useful.
I hope to have answered your query satisfactorily.
Take care and please keep me informed of your progress.
Good Luck !
May I request you to rate your experience here before you close.