Brown Discharge/ Pulsating in Early Pregnancy?

Okay, so I'm freaked out as most first time pregnant women may feel from time to time. I'm roughly 5.5 weeks pregnant, had some brown spotting on underwear, later had a gooey like brown discharge (very little) when I wiped. Called the doctor, they say it's completely normal but to watch it. Then I'm laying in bed and feel like a pulsating feeling in my uterus area. I did some reading and all I could find was it's the extra blood flow through a large vein that is pumping to the embryo. This happened for about 5 minutes, but still weirded out and worried. Has this happen to anybody? If so, was everything okay?