What can I do if all of my appeals have been exhausted?

Cigna has denied my husband’s Short Term Disability. He has Vertigo and is unable to work. He has seen our family physician, a neurologist and an ENT specialist. All have the same diagnosis – vertigo – and tell him he cannot work as his work involves driving. The first time he sent in paper work from our family doctor, he was paid. After a week he tried to return to work. He worked three days and the Vertigo was so bad he could not continue. When he submittted paperwork from that doctor visit, his claim was denied. According to his representative at Cigna, their physician reviewed the reports and deemed him able to work. How can a claim for the exact same thing be approved on week, and denied the next? We have appealed with every doctor visit and they still will not approve his disability. He saw his ENT today, and was prohibited from working for another four weeks. Is there anything else we can do at this point?