I had never heard of it before today.
I thought perhaps he had a parasite
or something more benign than this death sentence disease.
I had never heard of it either, when my precious Munchy got it. She had the wet form of the disease, which kills very quickly. We had to have her put down as soon as we got the diagnosis. It was a similar situation with our other FIP kitty.
Make the most of the time you have left with your little fellow, and be glad he doesnt have the wet form.