Brown discharge with walking?

Melissa
Hi Al, I am almost 36 weeks and am 1cm dilated and having a ton of Braxton hicks. Past few days have had a good deal of brownish discharge, most noticeable after I take a walk or exercise at all. Anyone else have this? Could it be from my cervix dilating more? Mucus plug? Seeing dr tomorrow but I hoped to get other experiences/input.