Suggest Treatment For Premature Graying Of Hair With Hair Fall

Hi doctor i am 17 yrs old and i am having grey hair .I have a lot of hairfall after bathing.I feel very shy when i go out.I apply heena(mehendi) on my hair. Is it safe for my hair?. I masturbate once in a day .Does it have any connection with my hair greying.Moreover i suffer from constipation many times will this lead to hair greying .Doctor please help me out as i want my normal black hair back.I have this problem from the past 4 yrs.Please help me out..

Thank You