Early labor

Currently 31 weeks with my fifth babe and I'm looking for experiences from mamas who went into preterm labor before 35 wks. What symptoms did you have? I've had a lot of spotting this pregnancy ( I didn't experience it with my other 4) and Idk why but I feel like I'm going to have this baby early. This week when I hit the 31 week mark, I had two mornings of brown discharge (not mucus plug) I monitored it, it was only when I wiped and then nothing yesterday. Today I woke up and had brown/pink discharge when I wiped (again not mucus plug and I'm not constipated or had sex within at least 10 days) I put a call in to my OB and they were dismissive. Said not to worry and if I was concerned to go to L&D to get checked. My only other symptom is increased Braxton hicks, nothing timeable or so uncomfortable I can't handle them. What are your thoughts/experiences with this?