Hairfall at 21 without any family history of baldness

Patient: I m 21 years old. No one in my family is bald . When i moved to college hostel in another city, after 1 year I experienced heavy hairfall. Not only me , most of my friends suffered from heavy hairfall in the hostel. At any time you can see young students with shaved heads in the hostel in hope to control hairfall.Can you suggest what is the problem. It cant be male pattern baldness since suddenly many people began to loose hair. My hair is falling for one year now from every part of head. Was something wrong with the hostel food or hard water of the city where my college was..ThanksParker

Symptoms: Heavy Hairfall at 21