Shingles can be a very tough condition and very serious when it involves the eye. I am glad you are recovered and that your vision was not permanently damaged. Vitamin A is an excellent natural anti-viral but due to its fat soluble nature it can also be toxic. It also has a drying effect on certain secretions in the body which may be why you are having some eye irritation when you take it. I would suggest that you discontinue it for now as there is little reason to stay on it if the shingles infection has passed. The itching reaction to the b-vitamins has to be related to a binder, filler or additive in the supplement. B-vitamins occur in nature and if you had a true allergy to one of the b-vitamins it would happen when you eat food. I suggest trying some different b-complex products and shopping for products that have the least amount of additives, fillers or binding agents (typically listed on the area of the label marked “other ingredients”). Quercetin is a potent bio-flavinoid with many important health properties. One of its most well studied actions is to help stabilize mast cells in the body which can reduce histamine reactions related to allergies. In health, Dr. Passero