Please help

We did bloodwork and 2 xrays. Saw 2 vets and neither could diagnose the problem. Over the past year or 2 she has gotten more and more affectionate, more vocal, and has been throwing up more and more. She used to have a hairball weekly, then it turned slowly into plain vomit once daily or every other day. She then suddenly stopped throwing up, stopped eating and started to hide. She still liked her favorite foods, but now is refusing more and more. Please help me find her problem.

It is not unusual for vets to return a set of blood tests and a couple of X-rays, saying 'we don't know what's going here (yet).'  However, by this stage they have usually successfully ruled a number of worrying things out.  Two useful next questions are:  'What's at the top of the differentials (possible diagnoses) list now and can we test for that?' and 'Is there anything we should be doing right now to help the symptoms?' (For example, dehydration from vomiting might require a drip, whatever is causing it; a bland diet might make vomiting less likely).  You might also want to ask whether your cat needs you to treat the symptoms or test further.  Some differentials that your vet might not have ruled out yet might include pancreatitis, which doesnt show on most routine profiles and may need special procedures to diagnose it, a dietary indiscretion that may pass or indeed, something like a tumour that will not.   It sounds as though close communication with your vet will be very important at this point.