Suggest Medication For Severe Cramps After Having Periods

I started my period April 28 and ended May 4 which was unusual because I only go for 7 days. okay May 6, a day after my period was over I started cramping I took a tylenol p.m. pill and all it did was put me to sleep. I woke up today and I am still cramping so my question is why am I cramping when Im not on my period