Dandruff & dry skin from 12 years.

Hi , my age is :24 years I'm having dandruff and dry skin problem from last 12 years. I have already tried different type of treatments , but nothing worked. I need to do shampoo on daily basis & apply oil after that , as my scalp gets very dry and starts to form a very thin white layer on scalp after a while. There is formation of a dry skin on back of my ears and my feet nails also looks torn(not smooth). Even in summers my body skin is very dry and have to use oil instead of moisturizer . Please try to relate all of these symptoms together and suggest , as one of the homeopathy doctor suggested that my intestine has been bit dried up or there is dryness in my body internally (not sure) and all these things are happening because of that . Suggest on this and also please let me know - what type of treatment would be suitable for this condition .