Farting Old Lady

A little old lady goes to the doctor and says, "Doctor, I have this problem with gas, but it really doesn't bother me too much.  They never smell and are always silent. As a matter of fact, I've farted at least 20 times since I've been here in your office.  You didn't know I was farting because they don't smell and are silent." 

The doctor says, "I see, take these pills and come back to see me