Please take him to a pediatric neurologist to rule out Gullian Barre Syndrome, amyotropic lateral sclerosis, Lyme’s disease, polio and post-polio syndrome,
multiple sclerosis, motor neuropathy, and spinal muscular atrophy.
EMG, spinal tap, MRI of the cervical spine, nerve conduction velocity tests will be required to nail down the diagnosis along with detailed history. It will help if you can chart his disease progression systematically to help nail the diagnosis. Take care!