Spotting while pregnant

Keirsten
So I am 6 weeks pregnant. I saw the baby for the first time last Wednesday and go for the heartbeat this Wednesday. TMI but I have been a little constipated and had some trouble using the restroom.. And tonight while trying to go I felt a sharp pain in my abdomen.. When I went to whipe there was some light brown/kinda pink ish cm on the toilet paper. I am panicking and I am wondering if this is the start of a miscarriage or if this is normal ?! Please help! I am so worried