Kitten Throwing Up

Hey all, I'm brand new to posting on this site!

I work at a place that has a horse barn and we recently adopted kittens to stay there. One of them is currently living with me until he gets a little bigger. When I adopted him, there were no specifics in his chart about his age other than "kitten". My guess is that he is around 3-6 months old. My question is: he's been throwing up undigested food and sometimes just dry heaves (for lack of a better word). Today, instead of giving him any dry food, I have just given him wet. He still threw up, but there was less undigested food and more just liquid (I'm assuming stomach juices...ew). He is drinking water, playing like a kitten, using the litter box regularly. I've also started giving him something for hair balls, just incase that's what it is. After reading several forums paired with the fact that he's still eating and pooping, I'm starting to think (and hope) that it's just because he's eating too fast. Any ideas on what could be causing this? also, I'll take any ideas on how to get him to eat an all wet food diet slower! Thank you!! 

EDIT---- it's been two hours since he was last fed (all wet food) and he just threw up. It was mostly just water (he just finished drinking a lot) and a couple small bits of food. 

Has he been dewormed?

Has he been dewormed? Because it isn't normal to continuously throw up. Is it after every time he eats? Either way I think he needs to be checked out by a vet.

Thanks for replying, yes he had been dewormed. I have read several posts about cats/kittens throwing up from eating too fast. I am going to research ways to help him eat slower. If there are no improvements with those changes, I definitely plan to take him to see a vet. 

You may want to feed him only small amounts at a time. Have you tried that? Yes if they are used to competing for food they will inhale their food and then throw up.