Feeling worse after B12 Injection: Answering concerns. La Vie Med Spa Feeling unusually tired and fatigued? Having tingling sensations in hands and fingers, or having balance and memory issues? These could be symptoms of Vitamin B12 deficiency. Get a comprehensive check with our Still Tired After Illness? When to See a Provider HCE I Feel Tired All the Time. Do I Need a B12 Shot?: Shawn Veiseh, M.D.: Family Medicine