blood blister on nipple

Mandy • Endometriosis dx 2015. MC Sept 2016. 🌈 baby Grace 11/26/2017.
I've searched google up and down and have only found this happening from latching problems during breastfeeding, or pumping. 
I'm not breastfeeding and am 16 weeks pregnant. Nothing new that could have caused this! Has anyone else experienced this?! It's painful and bleeding!