I've been exclusively pumping for 3.5 months and never had this happen. It's not painful and my nipples are not bleeding at all so this had to have come from inside the breast not just from bleeding nipples. Also, when I dumped it out it was a huge clot. Dr Google is of course "could be breast cancer" and very scary...please tell me this is normal?! I was planning to quit pumping at the end of this month but may quit sooner if this continues. If it continues I will of course contact my dr but just wanted to see others experiences too.