cat very sick ?

I just need to know if anyone has gone thru this. My Persian Calico is 12 y/0. She became very ill last year and never really figured out wht happened . she was tx with anti-biotics but it was touch and go. She has been fine for a year. 6 days ago became ill. no appetite, very lethargic. took to vet. xray, blood work, etc. Kitty sent hm. Still no appetite, no liquids. So, I was referredd to a Specialist. They then proceeded to do Ultrasound, urine test, T-4 , etc. All normal, so then I am referred to a Neurologist!! This was just yesterday. I took her back to the dr and she gave a steroid shot to stimulate her appetite. She came hm and did eat some. However, still lethargic. Dont know wht to do dont want to lose her. I am broke but this has already cost 1,300. in 6 days!!!