Weird Vomitting

Hi Guys, I'm new to this so here it goes.
One of my boys who is 9 years old has developed this new symptom from last night. So I was sat in the lounge and heard a cat meow, I say a cat, it was mine but I had never heard him meow like that. Following this he was retching and chicken head bobbing (sorry only way I can describe). He then Vomitted, I say vomit as I have read that regurgitating is effortless. He Vomitted undigested food (if course in the carpet) following he like retched/coughed for about 3 hours. This was brought on when he changed position I.e grooming etc. He was then hungry again, when are they never hungry!!! Kept him in all day as he is very much an outdoor cat. Came home from work to no vomit and he had eaten. However it has happened again tonight he hasn't been sick but the retching again. He is normal in behaviour maybe a little more clingy.
He is an outdoor male, had since a kitten and only past vomitting with fur balls. No hair on this one and no bile or fluid. He is fed both wet (delis senior) which he has had since he was 7and dry food (James well beloved) and has dreamies as treats which he adores. Never been a sickly cat.
Any ideas?

You should probably get a vet to check his mouth.  The weird howl you heard was probably what we call the "pre-barf warning" which is a noise cats make when they feel a barf coming on.  Not just a hairball barf, but one of those deep from way down explusions of everything they have eaten for the past few hours. 

One reason he is doing this could be that he has a bad tooth, and because of that he is not chewing his food, and if yu are feeding dry food, he swallows it  whole, then drinks water, the food swells in his stomach, and there is no room so he throws it up.  I have one cat who does this and had to get a special dish (made for dogs) with some shapes in it that make them slow down their eating.  That has worked for her because she no longer wolfs her food. 

Other than the bad tooth theory, if he has done this two nights in a row, he may have eaten something that has blocked hiis intestine at some point, so all the food he as eaten has come back up.  You should keep him in and watch to see if this happens again.  You could also feed him wet food, because if it's the not chewing problem, feeding wet food fixes that since the pate and loaf styles do not need to be chewed.  (Avoid the kinds with bits and pieces in them)

Thanks so much for your reply. I'm keeping him in tonight and see how he goes. I have just let him eat wet food and he does have an appetite. I will book him into the vet tomorrow. I am a nurse and have had a look in his mouth which seems ok and he doesn't look in any pain when eating.

Let us know what the vet finds if anything.  Sometimes bad teeth don't show on the surface, the problem is underneath, where they have an abscess.  At 9 years old, he should probably have a dental cleaning if he hasn't had one in awhile.  They dont show pain when eating because they just swallow the dry food whole to avoid chewing.  We would do the same thing!  The wet food having 78% of moisture to start with shouldn't be any problem whether he chews it or not, but if he has an intestinal problem, the wet food will come back up also.