Unfortunately it seems that your guy has developed a new problem called hepatic lipidosis.
Cats that go for more than a few days without eating are at risk of developing a condition called hepatic lipidosis or fatty liver disease. Overweight cats are especially vulnerable.
When a cat stops eating, their body begins to mobilize fat stores for energy. Some of this fat is deposited in the liver. If a cat is not taking in any protein, then it does not have the building blocks needed to make the substances that are responsible for getting the triglycerides (fat) out of the liver. The accumulation of fat within the liver leads to swelling of the hepatocytes (liver cells) which in turn causes a back up of bile flow through this organ. The end result is liver failure.
Whatever the initiating cause of his illness, he is now suffering from liver failure. Hepatic lipidosis alone can be difficult to treat. It is vital that he get some nutrition in, whether by force feeding or via esophagostomy tube (surgically placed into the esophagus, bypassing the mouth), or jejunostomy tube (placed in the small intestine).
Intestinal parasites do not cause such severe disease. It is something much more serious like those options mentioned in my initial post (diabetes, hyperthyroidism, cancer, or other underlying disease).
In these economic times, unfortunately many people are in your situation and have difficulty affording more than the essential things. His illness will be costly- they will want to start with a physical exam, blood work, perhaps x-rays or ultrasound in order to determine the underlying problem. Actually treating his issues will obviously run into a good deal more money. If you can borrow from someone, work out a payment plan with your veterinarian, or look into Care Credit (www.carecredit.com)
, you may be able to get the money that way. If you aren't able to, then I think euthanasia may very well be the kindest option for your boy.
I'm sorry that you and your boy are going through such a difficult time.