I think my bunny is going to die and I don't know what to do?

Brownie is usually very energetic and playful. He eats alot and he is very healthy. But somehow he lost alot of weight and there are some some spots on his body that have lost its fur like his ears, feet and his back. His eyes seem to only stay half-closed and he moves less and just lies in his cage all day. One day I let him out and he was barely moving. He was dragging his feet along the ground. He looked so helpless. His breathing was what got me scared. His breathing was going slowly everyday! My parents say Brownie is just getting old, but he is only 2 years old! I don't know what's wrong with him and I don't know what to do! Since my parents say he is just getting old, I can't take him to a vet. Please help!