Sharp pain in my anus/genital region?

Rectal Pain: There are a number of things that can cause this, but in order to diagnosis it we need a more history such as when it occurs, has there been any trauma, are you sexually active, is there any bleeding, any lesions, etc. That area also needs to be examined. So what you need to do is go to a doctor or a nurse you trust and get examined, take a trusted female adult with you.

What preceded pain?: Did you strain to defecate? Was there blood on the toilet paper? Assuming no other trauma at your age the most common cause is a hard stool tearing the rectum. It should heal on its own in a few days. If this is the cause increase the fiber in your diet and increase your fluid intake. If this is not the cause go see you doctor.