Bleeding at 12 weeks

We had a scare last night. I started vaginally bleeding bright red blood. We went to the ER and they did blood work, hooked me up to IV fluid, and got a urine sample. I was still bleeding when we were there. Not enough to fill up a pad or tampon but when I wiped it was still bright red blood. Doctor eventually came in with a ultrasound machine and spotted baby dancing and moving in there with a heart rate of 158. Everything was good! Blood work came back normal, urine sample came back with possible UTI so he put me on antibiotics. He said there multiple reasons for bleeding but it can also be normal. He said just to follow up with my OB. This morning the blood turned brown and stringy, similar to the end of a period.

Has anyone had a scare like this?

TMI for the photo