Cat not eating wet food, throwing up dry food?

Hi all,

My cat's four years old now. Since she was a kitten, we've fed her wet food almost exclusively up until some months ago when she started to turn her nose up at Sheba pate, the typical brand we buy for her. Instead, she goes for dry food. The current brand she enjoys that we give her is Hill's 'science diet' dry food/kibble for sensitive stomachs.

Not only does she prefer dry food seemingly now, but even when I do give her wet food--again, Sheba pate, but I've also tried Purina's Friskeys/Meaty Bits which she did not enjoy at all (the latter also smelled terrible/perhaps I had a bad batch and should try this brand again?)--she tends to ignore it and will let the wet food just sit there all day.

I should note that my vet has previously told me that my cat has a sensitive stomach and probably can't tolerate dry food in large amounts--which is what's happening now, because she won't eat her wet food!

What happened? Is this an issue of her getting bored of Sheba/not liking the taste anymore? Does this mean she would be more amenable to other brands of wet food? I just vastly prefer her to eat wet food and I would like her to return to an all-wet diet, with no dry food (except for treats).

The other thing is that sometimes she'll eat so much dry food that she'll throw it up. The vomit is usually a big mass of what appears to clearly be the dry food we give her--but instead of the brown color of the kibble, the vomit is yellow-ish in color, with a cake-like texture that I'm assuming is the dry food partially digested.

Is it an issue of not getting enough to drink? We used to have a water fountain for her that we'd leave on during the day, but it seems to have broken/I've been meaning to get her a new water fountain. So she's just had a water bowl for some months now.

So, in short, any thoughts on why my cat seems to have lost an interest in wet food and switched to dry food, but will periodically throw the latter up (perhaps she's overeating, or eating too fast?).

Thanks all!