What do you want at the doctor's office?

Yesterday I was driving my kids home from daycare. We always pass by the doctor's office on our way home and my son Jonathan knows it. He knows where everything is around town actually. As we passed by yesterday Jonathan said, "Mother," that's what he calls me now because my husband tells him not to hit his mother or say no to his mother, etc., "Mother, I want to go to the doctor."
I said, "Jonathan, you dont need to go to the doctor. You only go to the doctor when you are sick or need a check-up."
He thought about it for awhile and spoke up again, "Mother, I want to go the doctor, get ketchup."