Armpit fat/ swollen pregnacy

Ok so when i was pregnant with my first baby my left armpit got fat . then a couple days after i had my baby the same armpit got really swollen . but it went down maybe like 2 weeks later ? I didnt breastfeed i guess when my milk supply went away . so the swollen went down but it still left me with all the left over fat ... Now im pregnant with my second and my right armpit is getting fat now im scared its gonna get really swollen after i have him and leave me w all this left over fat ? Is there a way i can prevent this or do i need to get surgery or something? has anyone else gone through this?