can be because of central(brain) or perpheral vestibular system(ears).
You need to get done--
1. get yours ears checked
2.get done pure tone audiometry
3.depending on the result of above test further tests are advised for nerve conduction .
4. MRI brain with contrast specially to look for posterior cranial fossa
See all these tests can be done under guidance of an ent specialist
and in addition he will do some clinical tests for vertigo
5.Get your B.P. recording 6 hrly and chart it.
6.Avoid alcohol and smoking.
7.Get Blood sugar testing.
Report back.SO that If i can be helpful to you.