Welcome @van2604, Sorry to hear that you are not able to sleep due to the pain in your left hand. There is another related discussion that your husband might find helpful to connect with other members with the same condition to learn what they have shared.
-- Does anyone have CBS (corticobasal syndrome)?
https://connect.mayoclinic.org/discussion/cbs/
If it's an option for you, Mayo Clinic Jacksonville would be a good place to have your hand looked at. You can find more information here - https://mayocl.in/1mtmR63.

I have pain in my hands that sometimes keeps me awake but it's not connected with my neuropathy. I have carpal tunnel along with degenerative arthritis in both hands. Mayo Clinic has more information on carpal tunnel here - https://www.mayoclinic.org/diseases-conditions/carpal-tunnel-syndrome/symptoms-causes/syc-20355603.

Is the pain just in your left hand?