Thanks for writing in.
I think you probably pulled a muscle during the crunches. Its unlikely that the protected anal intercourse caused any of these symptoms. When you start with an exercise, please make sure you maintain a proper posture. Do not do more than 6-8 repetitions in one go.
At this point, the pain can be relieved by using diclofenac
gel and hot fomentation ( in the form of hot water bottle or electric heating pad
). This should make the pain much better.
Hope this helps