Scary Morning

I spent my morning in the er because I woke up and was bleeding I'm 11 weeks and 3 days, I freaked out and went right in to the er. They gave me a transvaginal ultrasound, and what seemed forever I finally got some word. the baby was on the heart beat was good my cervix and uterus are ok, I ended up getting a shot because they said my blood type is O- this is the first time I've ever heard of this and I was a little confused. They told me I have a higher risk of miscarriage which really has me worried, is there any other ladies who have a negative blood type that went thru this? I'm literally so distraught.