Freaked out or not, please go get that checked. You could either have internal hemorhoids, or you could have broken a blood vessel in your rectum. I don't know if they can do a colonoscopy at this point in your pregnancy, but your OB can find out from a gastroenterologist. I am sure that they would find a spot for you in their schedule if you need this. It is really a big deal that you have a family history, so don't let this just ride.