Cramping but no period.. HELP

My boyfriend and I had intercores with out protection like 2 weeks ago today. My period is a week and 3 days late. A couple of days ago I had on and off spotting. I would spot this darkish red/brown color and then a few hours later it would stop. I notice that I started spotting again but the color had changed to a brighter red/pink color. I notice that it wasn't heavy enough for a pad or tampon so I just used a underwear liner. I'm not sure if I should go see my doctor or just wait it out.