know a good websites on determining what's wrong with a cat?

Please get your cat to the vet ASAP if you have not already done so.

Our big older guy, Dactyl, went into heart failure just over two years ago. He was crouched down, breathing hard, not at all social... We took him to the vet and they said that his lungs were filling with fluid as his (enlarged) heart was failing.
At the vet they gave him medication and helped him out... We have to give him medicine three times per day (he's very good about taking it). Months later we took him for another ECG and they said that his heart had gotten a little smaller (which is good, in his case).
I really hope that your friend's cat can get help and feel better soon... Please let us know?
Having a sick cat, a member of your family who you love, is SO stressful. No matter what happens your friend seems to really love the cat, and that means your friend has given the cat a good home...

I'm so sorry. Please send your friend my condolences. Your friend gave his kitty a good home and lots of love, I'm sure, and I bet the kitty really loved your friend. I'm sorry.