Lump

I am a 33 year old over weight female. Last night while bathing I found a pea sized knot in the center of my right armpit. This has me very worrried. I am currently on my period so i am hoping maybe that is the cause. I had a mamogram (mammogram) roughly 2 years ago that came back normal. Should I be conserned???
Thank you

[CCF-RN,MSN-rf]

Dear sandy1969:  If this is a pea-sized knot in your armpit, it could be a pimple or ingrown hair.  I would keep an eye on it for a week or so.  If it does not go away, you should call your doctor.

[Sandyh]

The lump is not visable its under the skin. I can see it, only feel it. Could it still be a pimple or something like that??