Strong abdominal pain light spotting days after period..what is this?

I finished my period 5 days ago now and this morning i had very strong abdominal pain came on very suddenly...was hunched over couldnt move...lasted few hours..i still have discomfort like period pain...feels like period is coming on..i went to doctor he seemed to have no idea..have another app with same doc on fri...might try and get a ultra sound to make sure everything ok... has anyone experienced this??? what could it be