My kitten vomits everyday

How long has this been going on? How old is the kitten? What are you feeding it?

Maybe a week, he's 4 months, dry food. I'm really worried.

You need to take him to the vet. He never gets wet food?

Could be some illness, could be food allergies. If it's suspected it might be food allergies, I would not go with some crapola the vet tries to give you. Most of that stuff isn't good quality food. Stick with canned (not dry), no seafood, no beef (check ingredients), NO GRAINS foods for a couple of months and see what that does. Even if it's some illness, that's a good diet for a cat anyway. After all, they eat small animals in the wild, not dry kibble.

As difficult as it is to give an opinion on such a problem online anyway, I would prefer that you would have been a tad bit more thorough on describing the condition of your kitten.
Details like, food she's on, how much, how often, how old she is, how often she's vomiting, how long she's been this way, the consistency and color of the vomit (is it just food, bile, hairball), has she had any shots, how long you've had her, etc should have been things you included in your query from the get go. The only piece of advice I can give is get to a vet, ASAP!

Yes she might just need worm medicine, sometimes the worms can block the digestive tract in a young animal. Take a stool sample along to the vet's

This poor little mite needs a vet asap,my kitten had similar symptoms and got very dehydrated very quickly so its really important that you see someone about this.

My kitten's (which was about 4-6 weeks at the time) digestive system couldn't cope with the food(tinned food) I was giving her and I had to get special easily digested food sachets from my vet, this was mixed with water/milk and after a few weeks I was able to reintroduce the usual tinned food I bought(especially made for kittens) she is now in very good health.

Hope your little kitten is OK too