After the first bite of food, throat will block up?

My son is a 32 yr old 6′ 2″ 195 lb seemingly healthy man EXCEPT sometimes when he eats within the first bite of food his throats will block up. It will constrict causing pain but relax. Sometimes after a minute or more the food will work it’s way down and he can continue to eat but on many occasions the food will not go down. He can not eat or drink anything as nothing will pass he then will have to make himself throw up to dislodge the food. But will not then be able to eat for a long while. This might happen15-20 times a month. He has tried drinking before he eats but makes no difference. He has had the problem for about 8 years. Because of no insurance he has not tried medical treatment. As his mother, I am very concerned for his health. There doesn’t seem to be any particular food that triggers the problem.