Atlas adjustment can help with pinched nerve and numbness and tingling in hands and legs.But both the cerebellum and vestibular organs are above the neck so it cannot help with dizziness is my opinion. One thing I did find is sub occipital tension is there due to migraines. A good chiropractor can help with this. Sometimes the sub occipital trigger points if sore can trigger migraine on their own.
I was told if SCM is too tight can cause dizziness and so can TMJ but I doubt that chronic dizziness and migraine can stem from thsee conditions