What could cause muscle spasms in hands and feet due due problems with cervical spine disks c6-c7?

Nerve compression: Anytime the spinal nerves are compressed or irritated there can be pain from the point of irritation all the way to the end of the line( your feet). Relieving the pressure on the spinal cord will lessen the pain.

Spinal cord compress: To have symptoms in both the arms and the legs, this is more than just a pinched or compressed nerve root. It is a compression across the spinal cord at the c6-7 level termed a cervical myleopathy. This is either a large disc herniation or a disc herniation in the presence of spinal stenosis. You need to see a spine specialist for an urgent evaluation.

Dystonia?: I would be worried that you are developing myotonic or dystonic problems. The MRI results may be incidental. I would suggest a thorough neurological evaluation first. Poor relaxation of the hands or feet with painful spasms could suggest myotonic dystrophy or a form of dystonia musculorum deformans. Cervical discs usually just cause pain down the arms. Another concern would be ms.