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First and foremost, it is not possible to diagnose a medical condition without a physical examination.
The causes of hairloss, fatigue, skin changes, and changes in body temperature etc can not only be a indicator of nutrient deficiency but also can be due to endocrine disorders like hypothyroidism.
Hence you should first consult with your doctor and get a physical examination done. In case of clinical suspicion, blood tests can be done to confirm the cause of your symptoms.
In the mean time proper nourishment, good hydration, use of sunscreens, avoiding severe sun exposure and use of moisturising creams can help improve your skin appearance.