Hello! My name is Dr. Aida and I am glad to attend you on Healthcaremagic! Your symptoms seem to be related to an inner ear disorder. As Zofran ODT is not working any more, I would recommend going to the ER for a physical exam and some tests. You may need to start other more aggressive drugs against vertigo and probably stay in the hospital for some days. Hope you will find this answer helpful! Best regards!