Hello. Our beautiful cat has always had a dodgy tummy. As a tiny kitten she shat /leaked poo everywhere but it settled.
Since then she's been a vomiter (intermittently but with periods where it gets more frequent). So,she's on a prescription diet from the vet for easy digestion. We feed her chicken as well as she was getting thin. Periodically when it gets bad I feed her white rice mashed up with tuna or chicken and that helps for a while.
She's also a scavenger and seems constantly hungry. She even ate the fluff out of DHs sock the other day
(not envy). She eats scraps off the floor, bread we put out for the birds, anything.
But recently she vomits all the time. Sometimes twice a day. We can take her back to the vet but they just can't seem to find any cause. Just that she's got a sensitive stomach.
She not got worms and there are no hair balls in the vomit.
We have puke stains all over the carpet. 
Any advice or thoughts ? I hate to see her suffer.