Constant tiredness even after proper rest? Feeling dizzy, weak, or noticing tingling in your hands and feet? These are not normal everyday symptoms they could be early warning signs of Vitamin Feeling worse after starting B12 : r B12_Deficiency Feeling worse after B12 Injection: Answering concerns. La Vie Med Spa I Feel Tired All the Time. Do I Need a B12 Shot?: Shawn Veiseh, M.D.: Family Medicine