Connection to metabolic disorders?

Please correct me if I have the terminology mixed up.  My specific problem relates to how my body processes all foods and supplements.  I think this is a metabolic disorder.

One specific example I have is this use of Biotin for my continuing hair loss and skin problems.  Biotin actually causes me to feel more fatigued and causes my cuticles to break and bleed, and receeds back the cuticle on the nailbed.

Now, before I hear about the side effects of this specific supplement, I have this problem with almost anything I take causing different side effects... Mostly fatigue.  Vitamin D gives me cognitive impairment and makes my hands and feet very cold.  Zinc for some reason causes severe pains in the chest area -- I believe is related to peripheral neuropathy.  Bioflaviniods make my skin extremely itchy and sensitive, and cause the skin to break open easily.

Whats the connection to peripheral neuropathy, and where do I get treatment for this kind of metabolic disorder.  If this is a metabolic disorder?