Dry scalp and dry and frizy hair.

Till 10 years of age I had very soft and silky hair .But after I had my periods at the age of 12, I had a lot of pimples on my face especially around my forehead  around this time only I noticed my hair had started changing its texture from straight and silky to curly/wavy and really dry and frizzy. Now I have dry scalp ,I have dandruff as well and dry and frizzy hair .I do regular oiling with cold pressed and lil bit of essential oils before shampoo,tried using sulfate &paraben free shampoos but nothing helps changing my current shampoo (dove)to any other shampoo results in hairfall and renders frizzier and drier hair. Let me mention that i don't use heating tools not even h air drier ,Ido not colour my hair I only use henna once in 6 mnth. I have hard water supply at home. Please suggest what all I can do to improve my hair quality.