Hello, this is Dr. David. I have read your question and I'm ready to help.
long term alcohol abuse can cause more than just B vitamin deficiency.
it can cause low folate levels and also low vitamin D
levels and low magnesium levels which can affect the nerves
you should take a multivitamin instead of a B complex daily to help restore any of these possible vitamin deficiency
and stop drinking alcohol all together
and start to eat a healthy diet
your symptoms could be early neuropathy.
there are nerve tests which are not painful such as a brain MRI scan and a spine MRI scan to check your nerves.
you should see a neurologist
you might benefit from physical therapy
to help strenthen your back muscles and leg muscles which can help your instability.
it doesn't sound like your autonomic system has been affected yet.
let me know if you have questions.