If you can afford it, you may want to have some more specific blood tests done on him. I did this with my Storm and he was finally diagnosed today with small intestinal disease. He's low in folate so I'm starting him on 400 mcg of Folic Acid each day for 6 weeks and continuing his 5mg of pred for 4 weeks. Hopefully this will do the trick. Vitamin B12 is also supposed to help increase a cats appetite. You may want to ask your vet about this.