Cramps, discharge, and curiosity

I am 18 weeks pregnant. I rarely get a brown discharge. I have cramps now and then in my back and going to different areas. I had two ultrasounds and several fetal heart rate checks and everything looked and sounded great. I go for an ultrasound on the 6th of February for my internal scan and gender reveal. I have had a few contractions I think. Do round ligament pains feel like cramps? I am pretty sure I am having a discharge from my growing uterus because I recently felt the stretching and gained weight. I feel so many new things. Is anyone having stuff like this at 18 weeks?