What Causes Abdominal Cramps During Bowel Movement?

I strained hard during a bowel movement and afterwards I had abdominal cramps for half an hour, feeling the pain down through my anus. I checked to see if i had done damage, and only when I defecate or flex my anus, that there is any type of extra skin exposed (as in..the continuation of my anus skin, only sightly pinker, not any other type of tissue). I think maybe i strained my internal sphincter muscles? My anus feels slightly looser but i do have control. I can still defecate easily but i feel like my sphincter moves around (never protruding). When I stand/sit, i feel like i have extra skin sitting atop the anal opening. will this require surgery or resolve thru pelvic exercise?