have you tried Cat Attract litter? It apparently has an additive to it that cats find irresistable and they use the box instead of pillows, carpet, etc. I just found out about it and am going to try it for Allen (he seems to think the litterbox is an optional thing) I too have gone the vet route and psychic route. He IS sick but we can't cure the infection because all the antibiotics we gave him made him sicker.... so the infection has to run its own course which is unknown. Anyhow,try the Cat Attract litter - it can;t hurt and it just might be the answer you're looking for.