Why do I get an armpit lump before periods?

There are a few reasons why you might get an armpit lump before your period. One possibility is that the lump is caused by swollen lymph nodes, which can be a sign of infection or inflammation. Another possibility is that the lump is due to a cyst or tumor in the armpit.

If you have any other symptoms, such as fever, fatigue, or pain, then it's possible that you have developed an infection or other medical condition and you should see a doctor. However, if the lump is only temporary and goes away after your period starts, then it's likely nothing to worry about and there's no need for further treatment.