Your armpit lump showing up just before your period often comes from breast tissue that extends into the armpit. Many women have this, and it swells with your hormones each cycle. It can also be a lymph node reacting to a small skin issue nearby. Your labial lump shrinking on its own fits a blocked gland or a settling ingrown hair, both common and usually harmless.
Next Steps
Watch both over the next week. See a gynaecologist in person if the armpit lump hasn't shrunk after your period, or if the labial lump hasn't fully gone.
Health Tips
See a doctor sooner if either lump grows quickly, turns red, or you develop fever or pus.