Spotting After Sex in Second Tri

TMI; I know, but my husband and I had sex yesterday. It was not painful and I did not bleed. I noticed after a trip to the potty 2 1/2 hours afterwards that I was spotting. It wasn't fresh blood, but pinkish brown. Still no pain or cramping. Then hours later I had cramping in my lower abdomen and upper thighs. Enough to keep me up from 10:30-3:00. Pain wasn't horrible but enough it made me worry some. It went away and I feel fine this am. I didn't have any more spotting after the first time. Anyone else have anything similar to this happen?