Anxiety B-12 and grey hair? can anyone shed some light?

I have recently been through extreme stress as a result of bereavement and my hair is rapidly turning grey as a result (in just a two week period). I read that anxiety causes the "fight or flight" reaction that requires your body's supplies of b12 in its recovery. I also read that a b12 deficiency can cause you to lose pigmentation in your hair. Could these things be linked? I also have extremely bloodshot eyes and pins and needles in my hands and feet, which i believe are also symptoms of b12/iron deficiency. can anyone tell me if this is likely? and if so, are there any foods which will have a fast effect on the deficiency?