Brown mucus discharge

All is well this morning took my third test and it was positive. On here it tells me I'm 5 wks 2 days where as the pregnancy test said I was 2 to 3 weeks. Later this afternoon I felt this discharge went to bathroom and it was mucus and brown. I have a liner on now and it looks like brown discharge. This is my first pregnancy. I feel slightly cramps but more like a tummy ache than period cramps. Is this  anything to be worried or shall I just keep an eye on it and call my doctor tomorrow?