How To Treat Difficulty In Head Movement Due To Fusion Of C1 And C2 Of Cervical Bones?

Dear doctor,I am unable to move my head . My cervical x ray revealed that the cervical bones c1 & c2 has fused partly . the disc has disappeared. I use collar to support my head. what could be the reason for such a fusing of bones?. When my Dr. examined me he said my chest expansion is only 1.5 cm instead of minimum 2.5cm. Please advise .