I think i have hair fall because every time i shampoo my hair and/or brush it, i see hair falling. what could this be? is it that serious already?

See a dermatologist: Decrease stress. Eat a healthy balance diet which includes protein. Have thyroid levels and iron stores checked. See a dermatologist for evaluation and work-up. Topical Minoxidil twice a day is the only proven remedy to thicken hair. However, this treatment it is not appropriate for everyone (given the warnings, precautions, and contraindications). See and discuss options with a dermatologist.