I have had wrist tendonitis on and off for nearly two years and have had physio but it's not working. i work with children so can't rest it, help!

Tendonitis: This is likely related to overuse. Wearing a wrist splint will help. Occasionally an expert's injection of cortisone with a splint will be necessary.

Bracing?: If you keep using an 'unhappy' tendon, it is unlikely that it will resolve. There are wrist splints that prevent flexion/extension which still allow us to function in most situations. Applying ice for 15 minutes at least 3/day and taking an anti-inflammatory should slowly help the problem resolve.