Try elevating the food & water dishes up off the floor about 2-6 inches whatever is comfortable for your cat. This will keep his head above his stomach & the excess stomach acid he is producing from making it's way back up the throat when he's bending down to eat. Use a planter stand, phone book, upsidedown low box, pet supply stores carry elevated dish holders too.
Have a read through this thread or even just the summary post for now:
Early Stage Kidney Failure in Cat
If you have any questions feel free to ask
