BPPV is caused by free floating otoliths in lateral semi- circular canal. By Epley's maneuver the otoliths are maneuvered in the utricle thus causing remission of vertigo.  Epley's maneuver should be done by an ENT surgeon ( with proper training and experience ). Often more than one sitting is necessary for adequate control of symptoms. Diet has no role in BPPV. Consult a good ENT surgeon for the Epley's maneuver. Word of caution : sudden head movements causes vertigo in a case of BPPV ,so it should be avoided.