Pregnant and dark bowels

I just found out that I am pregnant. I was just pregnant 4 weeks ago and m/c I ended up going to the ER for a sharp pain on my left side. They confirmed that I was pregnant and did an ultrasound and didn't see anything except bowel. Which I overheard a nurse saying that it must have passed through my bowels. That was the craziest thing I'd ever heard. when all results came back the dr stated that He didn't know if i miscarried cause tests show i was pregnant. I am not bleeding. or if I was having ectopic pregnancy? He told me to follow up with an OB I can't an earlier apt for 4 days I am now having extremly dark stools is this a sign of internal bleeding or infection? please help