Khob khun maak for your greetings towards me for your New Year! I believe the reason the festival may have turned into a sad situation in some areas is the unfortunate, forceful influences of the Western World!
It was good to hear that you did challenge your doctor a little regarding your cat and the food/water. This is another problem Western influence has had on both people and animals-chemical treatments as opposed to natural. It sounds like you are trying your best anyway. There must be a kidney infection. I am happy to hear that he does drink water, however, something is indeed wrong if he will will only drink the water after eating dry food. Have you thought about giving him Cat Grass to chew on? Cats chew on grass instinctively sometimes when they are not feeling well. Also, my mother is happy to contribute some of her knowledge as she did attend college part time and has some knowledge of Veterinary Medicine in a natural/herbal sense. We will try to think of whatever suggestions we can give to try and help you. Right now, the Cat Grass may be the way to go. By the way, can you please tell me how to say "grass" in Thai?
In regards to the insects, I apologize as I believe that was the inaccurate perception of a New Yorker's/Westerner's idea of what people eat in Thailand! His name is Anthony Bordain and he is very arrogant and travels the world discussing different foods. What people portray to tourists about a particular country is often very misleading from the truth.