What's wrong with my cat?

By law, you are responsible for the cat. You have to provide medical care if needed - just as much as you are responsible for feeding him. If you cannot afford a vet, you need to call the SPCA and turn him over so they can get the care he needs. Have you called a vet? Perhaps tell them about your financial problem and they can discount the service. Either way, you must get the cat medical care immediately, he may be suffering horribly....and you wouldn't know it - cats will hide their problems well. Please get him to a vet or take him to the SPCA.