Large amount of brown stringy mucous like discharge after bowel movement

I had an u/s last week on Thurs and measured about 6 weeks. Had brown stringy discharge of an on a few days prior. I have been constipated despite increasing fiber (next on my list is prune juice) and after a bowel movement tonight there was a lot of brown mucous like discharge. No pink or bleeding but it was just A LOT. I have another u/s scheduled for this Thurs because the fetal heart rate was low according to the Dr and I'm just freaking the F out. I had a chemical in April and I just can't stay calm this time around ! Has anyone had this after a B/M?