A man goes to the Doctor

and tells him he’s been having terrible gas, but his farts don’t smell and they are always silent, so nobody seems to notice. The Doctor prescribes him a pill and asks tells him to come back in a week.
The man returns a week later and the Doctor asks if there had been any change in his condition. “Yes!” The man says. “I still have terrible gas, but now my farts smell horrible!!” “Great!” Says the Doctor. “Now that we have your sinuses cleared up, let’s work on your hearing!”