31 weeks pregnant and bleeding? FTM

Alice

I had sex at 6am this morning, it is now almost 2pm and I am still spotting bright red/light pink every time I use the bathroom. Not enough to stain my underwear but definitely there... Also having sharp pains in pelvic area, but I don't think it's contractions? I'm a FTM but never had this problem before during my pregnancy.. I know it can be normal, but how long should it last before I get concerned?