Based upon your description, this is most likely an external hemorrhoid that has "thrombosed" (clotted) and bled. However, other lesions of the anus can cause these symptoms, and since I cannot examine him, he should have this area examined by his doctor, just to be safe.
Sincerely/ Robert A. Wascher, MD, FACS
www.doctorwascher.com
www.oncoguard.com