Itchy cat losing weight

Eat and drink more than usual, but lost weight! Start refusing cat food, waiting for something different!  Very itchy, flaky, pulling out fur. Vomiting.  Bad breath. 11 years old neutered male.  For about year living only inside. I would like to understand it's some mites, scabies etc. or some illness?  (Kidney disease,  diabetes,  hyperthyroidism..?)

Hello!  You have correctly identified several diseases that this could be, some of which are emergencies.  I would be wondering about kidney disease, liver disease, diabetes, hyperthyroidism, pyometra and cancer amongst others.  If mites or other parasites are involved, they don't sound as if they are the only problem, so be aware that parasites do sometimes get hold when an underlying illness causes a drop in immunity. Vomiting can lead to dehydration and deterioration very quickly in such cases so we would firmly advise calling your emergency vet (or your regular vet if they are open) right away for triage.  All the best and please do let us know how things go.

'Triage' in this sense is the art of asking questions with a view to establishing how much of an emergency something is ie when do you need to be seen.