i'm assuming you've had him to the doctor and ruled out ear and throat infections, so onward:
how do you make him swallow? easy: you don't - it's a game to him. if you're still feeding him, try switching to finger foods and don't feed him any more - let him feed himself. when mealtime is over, take away what's left without comment or reaction. he'll eat or he won't - the one thing he won't do is starve himself to death.
if you stress and harp on his eating, however, you are setting yourself up for years of food battles and power struggles. every time he gets mad at you, he'll retaliate by not eating. food will become a reward/punishment system, not what it is: fuel for the body.
your job is to determine WHAT and WHEN he will eat. his job is to determine HOW MUCH or even IF he will eat. keep it to that and life gets a lot less stressful.