Little OrangeKitten - that sounds like exactly what happened to my Sapphire. Except it was not treatable. I actually had a feeling it might have been fibrosarcoma but didn't want to say so straight off because of the aggressive nature and dismal prognosis. I didn't want to upset fragrancehound and then find out I was wrong.

Gosh I hope everything works out for you fragrancehound.

p.s. I don't vax my cats now either. Rabies is not an issue here in Oz and there are no compulsory vax like you have.