I Have My Menses With Cramps, But I Am Having

I have my menses with cramps, but I am having to suddenly go to the bathroom and have severe painful diarrhea, my sphincter will clench with a severe burning pain with abdomen pain but then after the first intial output,nothing comes out, so to stop the contracting and pain, I hold the toilet paper pressed against my rectum until the pain and constriction relaxes ....normal with menstration