What Causes Large Painful Boil On Scrotum?

My husband has had a very large and painful boil on his scrotum for about a week now. We went to the urgent care on Wednesday last week. They said it looked as though it was ready to pop, so they gave him anti-biotics and something for the pain. The next day it did pop, and some pus/blood came out. But now for the past 4 days, he has been draining consisitantly. So much that he has to wear a maxi pad in his boxer shorts to prevent his pants from getting wet. However, today, the blood and pus is thick and clotting. So much so that if he squeezes the boil, he literally has to pull the pus out like a string. It is very thick and long. The boil itself is still there, very large and hard. About 3 inches long. Is this actually a boil and will this improve or should we go back to the doctor. He is being stubborn today and wouldn t go to urgent care but I am very concerned.