My Father Is 83, Takes Metformin For Diabetes For Many

my father is 83, takes metformin for diabetes for many years, drank alcohol (at times excessively) for many years and currently partakes in 1/2 glass of wine with dinner, eats a fairly standard north american diet of dairy/wheat/sugar....currently symptoms are nausea, dizziness, weakness, severe neck and shoulder pain (could be bursitis related), increased slurring and frequent confusion/forgetfulness, constipation, headaches....