Having your ear drums cut and having a foreign object placed in them will cause both discomfort and pain. The eardrum has to heal around the incision. Your coworker may have a number of problems associated with her ears that will cause pain, hearing loss, pressure and slowed healing, due to the eardrum being cut.
Any type of surgery will cause pain and discomfort and depending on what type of surgery you have, the loss of functioning and mobility with the associated body part. You are not this employee's supervisor or physician and you have no place questioning someone who had a medical procedure conducted for the betterment of their health. You are not a lie detector; you are a person just like your coworker who can succumb to illness or injury. Be more concerned about your personal character, because it is apparent in this post that you aren't concerned about this individual's pain or health, just whether you think they are lying or not.
Don't be silly or inappropriate; just be compassionate towards another person in pain. You might surprise yourself if you show kindness and professionalism verses what the bottom line innuendo of your question was really about. Be honest, use good judgement and don't question another's integrity (honesty). Question your own.