When I had tenosynovitis the first times, I went to the doctors a lot to ask for help. I got a many treats but nothing helped really. Here is a list of things I tried, maybe they help in your case.

Orthopaedic arrangements

Splint, cast, cortisone injections

Medication

Voltaren, Diclofenac, Amitriptyline, Katadolon

Treatments

Physiotherapy, hand therapy, osteopathy, homeopathy, acupuncture, ultrasound, curd packs

Investigations

MRT (magnetic resonance tomography), examination of the nerves in the arms, X-ray of the cervical spine