I had one with my 1st pregnancy and have one with this one as well. Never had bleeding with 1st, but on Monday I had a lot of bright red blood and cramping, ultrasound on Tuesday showed 3 cm subchorionic hematoma. It can be caused by implantation. They usually resolve without complications.
But you need to be on pelvic restricitions, no sex until it resolves, no heaving lifting and no heavy physical activity.