betta fish has not eaten in TWO MONTHS!!!

I have a approx. two year old betta fish who has been sick for quite a while now... 2 and a half months...? Out of the 2.5 months, it has not eaten in TWO MONTHS! Please help me!!! I used to feed it Wardley's Betta Essentials, but when I try to feet it, it 1) won't eat it, or 2) I have to crumble it up into little tiny pieces, and then when it eats even a tiny little morsel, it always spits it out!!! AHHHHHH help!
I love this fish very much, and I would hate to see it die after just 2 years.
P.S. I know that it doesn't have dropsy, ick, or an fungal infection. Also, the water temperature is around 75 degrees, and I keep the tank pretty clean (changing the water once a week.) My betta has no external signs of sickness except a little loss of color. I can't believe that it's still alive after two months without food!!!
PLEASE HELP!
Tnanks so much.

I have a feeling that you clean the tank in a too drastic way that shocks the betta.

Here are some instructions on how to do it

Clean the tank. Clear up any buildups on the side(s).
Clean your accessories. Be sure to remove any buildup on your plants, stones, and anything else in the tank.
Replace some of the water. Don't change all of the water at once, as the abrupt shift in the environment can harm your betta. You should only change about 50% of the water in the tank at a time. For the other portion, use clean water of about 78ºF. Be wary of shifting the water temperature too drastically when you reintroduce your betta to the tank, as it may affect your betta. Don't forget to add any water conditioner, aquarium salt, and anything else, as needed.

Keeping a spare jug of water is helpful.
You should do this partial water replacement about once a week for a five-gallon tank.
For a partial water change of 20% per week, it is not necessary to remove the fish. Simply reach in with a gravel vacuum (a siphon with a wide opening at one end) and "vacuum" the debris out of the gravel or other substrate.

Thanks for the info.
The problem is, I have read about people doing that, and I usually try to do what your instructions say to.
Right now my betta fish is floating in one corner all day. It hasn't really moved.
But I will try.

Hospital tank might be needed as it is better to quarantine when there is a problem and medication could be given safely.

There is a site that specialize in Beta fish maybe you'll more guidance there.
http://www.bettafish.com/

Although a Betta can breath air, it also gets oxygen through its gills, so if the water is polluted with a lot of uneaten food the fish is going to be sick. A Betta or paradise fish can be comfortable in a properly maintained desk top aquarium, but those little betta bowls they sell in pet stores seem pretty unreasonable to me. Once the Betta is in a good environment, try feeding a small amount of mature, frozen (then well thawed) brine shrimp. Good luck, and keep us posted.