Hi Beth, I clicked this article because it resonated with me and I thought maybe I could share something helpful, as I've been going through it with one of my own cats! He was vomiting, I kid you not, at least once every day for weeks on end. Every vet exam - blood work, x rays, etc - came back great. They made me do a round of antibiotics as well, which completely traumatized the poor guy. What I have found most successful is Hill's Science Diet Sensitive Stomach and Skin formula. My cat is prone to both vomiting and diarrhea, and this cat food is a lifesaver. We had to do a couple months on an expensive prescription food first but he seems to do great on this one.
Something my vet told me that I've been conscious of now is sweeping your home for anything a cat could get into that they shouldn't - plants, cleaning products, leftovers licked off of plates, candles, essential oils, literally ANYTHING. Cats are SO sensitive and the smallest thing could be upsetting their tummy.
Cats do not vomit for no reason. As their owner and advocate, it's up to you to solve the mystery and figure out what they need. I promise you that as much as you hate cleaning up vomit, your kitty hates being uncomfortable enough to vomit so frequently. Cats are very good at hiding pain.
It's easy to become frustrated and stop trying to help your cat, and just accept it for what it is. But the vets aren't wrong when they say it isn't normal, and I have a suspicion a lot of people just aren't willing to put in the work to figure out what's going wrong - oftentimes it means the owner admitting they need to buy a better quality food, or get rid of their beloved houseplants, or switch cleaning products. But I bet that if you're willing to write a whole article about this, you're willing to figure out what's wrong with your kitty.
It took me more than six months to get an unofficial diagnosis that my cat has some intestinal sensitivities. But I went from cleaning up cat vomit every day to literally never. It's worth getting it figured out, for both you and your cat. Best of luck to you!