it could be a variety of things. unfortunately, dizziness and vertigo can be symptoms of problems, or the problems themselves.
An ENG test determines if there is damage to the vestibular nerve. Your nerve may be fine with the problem being else where. there could be ear rocks (BPPV), an E-tube problem, a sinus problem, etc. all stuff that an neuro-otologist will look into in depth. (i personally don't like ENTs)
I know how hard it is to not have answers to why you feel the way you do. it can be very debilitating and scary. It took me about 1.5yrs to figure it out. You'll feel better once you see the neuro-oto. even if it is not an inner ear problem, he/she will probably give you some information to lead you in the right direction.
let us know how it goes and feel free to ask questions or simply vent out your frustration if you need too.