Hi. My friend's son (4yrs old) has a problem that doctors haven't been able to diagnose. It starts with his rectum/anus swelling...then it spreads to his penis and pelvic area/lower stomach. He complains of pain. The doctors have checked for worms and the tests have come back negative. One thing my friend has noticed is that when she gives him Zyrtec the problem goes away the next day. Do you have any idea what the problem could be?