What Causes Inability To Make A Fist With Left Hand?

I can not make a fist with my left hand. I have RA and have been told that I have mild carpal tunnel. I have been to a neurologist, had ultra sound on my wrist, CT scan on my neck, and nothing has shown up. I have constant pain in my shoulder blade/back (on my left side) as well. Been to a chiropractor, massage, physio, and had IMS. Nothing seems to help? I am now waiting for an MRI on my wrist. Any suggestions?