Brownish discharge after urination can be due to urinary tract infection. The cramps and pelvic pressure which come and go can be due to changes in the position of the fetus. It will be good to see your doctor for UTI and diarrhea.
I just had my cervix checked as well, and am a fingertip dilated at 34 weeks. That was a day ago, and I have a brownish mucus discharge as well. Did you spot after the pelvic exam??? If so then the brown is completely normal. At least that's what my doctor told me. If you didn't spot at all, check with your doctor asap in case it is an infection.
Dear: Without any delay visit the gynecologists because might be you are having an urinary (ovarian) infection.