Same tube, drink!
If he swallowed the pill and it got stuck part- way down, then it is probably in his esophagus (the tube from the mouth to the stomach).
Pills and food can get stuck if your insides are dry, or if there is a "stricture" (narrowing) in the tube. Drink lots of water to try to get it to go down. If he gets a burning feeling or acidy taste backing up from the pill, baking soda in warm water can help.