The main reasons for axillary bumps during the menstrual period include the following: 1. Consider the axillary bumps caused by the hyperplasia of the axillary parametrium. 2. Consider the axillary bumps caused by the hyperplasia and congestion of the axillary caudal lobe breast tissue. The axillary lobe of the breast is distributed in the axilla, and during pregnancy and breastfeeding, the hormone level will change and cause hyperplasia. 3, the axillary lymph node hyperplasia caused by the axillary bumps, you need to go to the hospital to do an ultrasound examination of the axilla to clarify.