Suffering From Brown Patches On Forehead And Body Getting Darker. Blood Test Shows Low Vitamin. Is Pigmentation Due To Low Vitamin?

Sir, I have the following skin problems, a. brown patches on forehead b. skin turned brown and thicker than than the rest on finger joints c. face atleast 5 shades darker than body I spent a lot on cosmetic stuffs like Kaya skin clinic etc with no appreciable improvement. My job requires frequent abroad travel and can t religiously follow the so called skin care regime (cleansing , sun cream etc) I had a history of gastric problems and recently consulted a renowned doctor. According to the blood report I have low Vitamine B12 (around 248) .. which is apparently the root cause of of stomach problems as well as hyper pigmentation. However, for the skin related issue I d rather get the final verdict from a Dermatologist and hence the questions - a. Does my skin condition have anything to do with Vitamine B12 deficiency ? b. How do I go about solving for the pigmentation problem (by now I m convinced that this is not about the skin surface .. have done many facials / hydroquinone creams / glycolic pills) If you could please set a direction through a response to the above