Hi, It Is A Week Before I Am Due To

Hi,

It is a week before I am due to start my period. I have been getting aches and pains in one of my armpits and breasts, also noticing that one of my armpits is slightly swollen. I am concerned this is a lump, however it is not defined, and I am not sure whether it may just be completely normal?

I went to the doctors previously and was reassured that my armpits were not swollen and it is nothing to worry about. Is this something that women experience prior to their menstruated cycle? I am 20 years old.

Thank you