Unidentified root cause of vertigo.

Dear doctor From past 3 years, my sister has been suffering from persistant vertigo, pain in cervical area, dyspnea, numbness of limbs. And she had taken consultations/treatments from the following department: 1. ENT - consulted two ENT doctors but no improvement in vertigo per their diagnosis of Ménière's disease. She had taken Stemetil MD and Vertin 24mg for more than a year. 2. Ortopedics - consulted one doctor but they could not detect the root cause and treatment with Vitamin D3 injections and calcium. But no significant improvements. 3. Neurologist - They did nerve conduction tests, and brain mri but no issues were there. They treated with Betahistine, Quetiapine, Trixide H, etc but not improvements at all. 4. Neurosurgeon - Consulted two docs but both said physiotherapy will heal it. We also did physiotherapy for a month, pain reduced by 20% but no improvement in vertigo. Till today, nobody had been able to find the root cause of it. Any suggestions what is this?