Hi Archus,
Did your last fast make you deficient in Vitamin B12 and D?
A. Possibly, but unlikely. Vitamin D is stored in the body within fatty tissues as being fat-soluble, so more than likely you were deficient in D before the fast commenced. Most all people are D deficient.
B12 is mostly manufactured within the intestine from bacteria and with the aid of something called "intrinsic factor". B12's manufacture is inhibited by the fermentation/putrefaction of foods in digestion when combining a predominantly protein food with a predominantly starchy food at the SAME meal.
B12 deficiency is also quite common with meat-eaters as well and not just vegans.