After Having Vertigo For The Past 3 Years At Least

After having vertigo for the past 3 years at least once a year; having B12 deficiency; fatigue constantly and just testing positive for Parietal Cell Ab I am reading about pernicious anemia which the specialist I will be going back to see suggested may be why B12 shots are not effective. Wondering what can be done diet wise to improve this if anything. I am vegetarian but I do eat fish.