For three days i had severe pain and some bleeding in the rectum when going to the bathroom.now i sometimes feel some pain, no blood.what should i do?

See a doctor: Common things are common. You likely have a hemorrhoid. But there are other causes of painful rectal bleeding, such as fissures. The only way to know for sure is to have an exam. Good luck.

FIssure: You probably have a fissure. It should be confirmed by a colorectal surgeon and therapy should be initiated before it becomes chronic or gets infected, in which case surgery can not be avoided.