Hard sore lump on outter rim of armpit

My underarm area has been sore and kind of like a itchy sore feeling. As I was feeling it yesterday, I felt a hard small lump right where the breast ends on the left side but higher along side of the armpit..not in the armpit but along side it.It feels like a pea hard lump is just directly underneath the skin and it's itchy sore.
I am pmsing and going to start my period some time this coming week and my breasts get sore and lumpy with my period and after my period they go away. I have had a mammogram last year and an ultra sound and the technician told me i have very cysty breasts.
When I was younger I used to get lumps checked out right on my armpit area where the hair grows as I would get itchy sore lumps there, the doctor i was seeing at the time told me it was a swollen sweat gland and it would go away..which it always did.
I phoned my doctor's office yesterday and explained everything to his assistants and she said it could very well be from hormonal changes because of my period. Should i wait til after my period is finished and get it checked out...I am scared. I try not to press on it every 5 minutes as the more i press on it the more it hurts and itches.
Any info will be greatly appreciated

[CCF-RN,MSN-JS]

Dear virgo57, It makes sense given the history you describe to wait until after your period to see what happens with this new lump.  If it does not go away then have it evaluated more thoroughly.

[virgo57]

I forgot to mention I have been sick with a high fever and have been on 2 different kinds of antibiotics and have just finished the prescription about a week ago. I am feeling better now but thought to mention that just in case that could make it swell in that area.
Thanks