Vitamins

• Unexplained tiredness - 5 points
• Brain fog - 5 points
• Breathlessness - 5 points
• Brittle nails - 5 points
• Brittle nails with ridges - 5 points
• Pins & needles (usually in hands and feet) - 5 points
• Swollen and / or sore tongue - 5 points
• Sudden diarrhea - 5 points
• Balance problems - 5 points
• General unsteadiness - 5 points
• Vertigo - 5 points
• Burning legs or feet - 5 points
• Tinnitus - 2 points
• Irritability / anger / impatience - 2 points
• Family history of B12 deficiency / pernicious anemia - 2 points
• Hair loss - 1 point
• Dry skin - 1 point
• Lack of concentration - 1 point
• Memory loss - 1 point
• Insomnia - 1 point
• Prematurely grey hair - 1 point
• Psoriasis / eczema / acne - 1 point
• Rosacea - 1 point
• Vitiligo - 1 point
• Anemia - 1 point
• Infertility - 1 point
• Dizziness - 1 point
• Bleeding gums / mouth ulcers - 1 point 
• Loss of appetite / weight loss - 1 point
• Numbness - 1 point
• Depression / anxiety - 1 point
• Confusion - 1 point
• Blurred vision - 1 point

It's impossible to overdose on vitamin B12 as it's a water soluble vitamin.