I Am 21 Years Old. My Hair Is Very Weak

I am 21 years old. My hair is very weak and keeps falling everytime whenever i run my hand through my hair. Recently i feel my hair has lost its density and my scalp gets visible. I use clips and rubbers to manage my hair so that no one can see my scalp.sometimes i feel that my scalp hurts at the rrot of my hair. All my hair fall from root. I m not usually tensed but thos hair loss is making me panick.And dont have any idea about the deficiency in my diet but i prefer outside food. The problem started 1 year ago and its still continuing. I have tried different shampoos and oils but no benefit.what is the reason and solution?? And also no one in my family has hair loss problem. I dont use hot irons or dryers for hair