Help! Pregnant! (This pic contains TMI)

17wks preg and had low back pain that went on my left and down there it more like pinching. I know that could be normal and can be my baby or uterus growing. But just now felt like a discharge and when I went to check and wiped saw a bit of brown discharge and a drop of blood. When I Wiped myself again there's nothing. No bleeding. I could feel my baby moving though. And the pinching and low back pain pinches comes and goes for a few seconds. This is my first pregnancy. And in my next appointment I will mention it. I'm not bleeding it was just a drop of blood. Not sure what to do or what it can be.