Re: PLEASE HELP!!!!
Welcome, and I'm sorry your Dusty isn't feeling well. Unfortunately, with the small amount of information you have provided, there isn't going to be anything anyone on the internet is going to be able to advise you to do, other than to take him to a veterinarian. A vet will be able to pull blood and within a short while, have some answers as to what is going on inside; anemia, infection and/or other more serious problems.
The symptoms your cat is showing could be from many different things, ranging from nothing worry about to something very serious and life-threatening. Cats are usually very good at masking pain/illness and any time one of them exhibits a massive change in behavior, that is usually a very big clue that something is wrong and what it is, needs to be figured out fast before they deteriorate further. This usually means the cat has to see the vet for some diagnostics; physical exam, listening to heart/lungs, temperature, weight, observation of overall condition and demeanor, blood tests, snap tests (for FIV/FeLV) and/or urinalysis.
Let us know how it goes. The information you share could help other cat owners who find themselves with a cat who has similar symptoms to your Dusty.
Best of luck,
I wanted to add...
Female cats come into season and some can express different symptoms, though usually lethargy is not one of them. To the best of my knowledge, male cats do not go into heat like a female cat who undergoes hormonal changes.