I had intercourse only a couple of weeks ago, with protection. The other day I noticed a light pink discharge which is normal before I begin my menstrual cycle. Needless to say, I am still waiting to start, but the past two days I have had light cramping and a heavy sort of fullness in my lower abdomen. Along with that there is also a slight pinching feeling, but not painful. I took an HPT yesterday evening and it was negative. What's going on?