Nipple piercing!

I’ve had my nipples pierced for over a year now and for some reason the right one starts bleeding out of nowhere. A little ball of blood will fill up on the side sometimes of one of the piercing holes. Sometimes it’s fresh blood and sometimes it’s dried. I don’t think I’m hitting it or irritating it unless it’s happening in my sleep. What I do notice is this normally happens during my time of the month when my boobs get bigger. So maybe my piercings just aren’t completely healed yet, and my boobs have increased blood flow! I don’t know. Someone explain, please.