Last Month My Nipple Was Swollen And Painful. I Went

Last month my nipple was swollen and painful. I went to urgent care and they gave me antibiotics and told me to see my on/gyn. I did that and she didn't have a solution and sent me for a diagnostic mammogram. That came back fine. After I finished the antibiotics my nipple looked fine. This month my nipple began swelling again and got a blood blister on it. There wasn't as much pain this time. The blood blister popped today while I was working and is still bleeding 4 hours later. Both times I had just started my period when symptoms began. I stopped breastfeeding a year and 2 months ago but still occasionally lactate. This month my nipple having issues is producing much more milk than usual. What could this be?