Oh Jena, that is so stressful! I'm pretty sure we are all familiar with the "following around with a towel" zombie walk. I'm so sorry you're having to do that so frequently.
Sam fakes me out with swallowing the pills sometimes too. One trick I've found is to have a treat at the ready and as soon as I think he's swallowed, I put the treat in front of him to eat. If he eats the treat, the pill goes down the hatch too.
Have you watched this video:
Sam isn't as nice (or as small) as the kitty in the video, but this technique does work reasonably well. One thing I've learned is that a hard surface is needed. If I try it when he's on a rug or furniture it doesn't work b/c he can get traction and get away from me. Another trick is pinching off a tiny bit of a pill pocket to wrap around the cerenia. Then when he does spit it out (which he usually does a few times before he swallows it) it's usually salvageable instead of completely destroyed. I swear he sits there and laughs at me every time he manages to spit it back out. It's like a game for him. He doesn't even run away. Just spits it out, laughs, and waits for me to try again.
Oh, more tricks....while her head is tipped back and after you've tossed in the pill, gently stroke her throat. This triggers a swallow reflex. Or hold her mouth closed gently and blow on her nose which is also supposed to make them swallow.
And mostly just patience, persistence, and some gentle reward for yourself once it's over! Pilling a cat is probably the hardest thing we have to do.
As far as the ongoing vomiting, it's possible that she's had low level p-titis for awhile. In many cats it can be a chronic condition and go on for a long time. It's also possible that she has IBD, an acid-y stomach, or a food allergy. There are a number of things that can cause ongoing vomiting in kitties, so while it may be something serious, it's really more likely that it's something more common.