My hair is falling ? (male)?

am 18 years old (male) and i noticed recently my hair is falling. My dad is not bald or anything like that. The problem is that my head hurts (the top-middle area) for no reason. It feels like if somebody pulled my hair so hard. I really don't understand why it hurts or why my hair is falling when i brush it. i have been taking Prevacid for about two months, because i have acid reflux. Would that be the reason? When i brush the top-middle area of my head; hair falls. But when i brush my left or right side; my hair doesn't fall. How can i treat this hair loss problem? How can i prevent it or know the cause? Why does my top-middle area of my head hurts?My hair is falling ? (male)?
you need a lot of vitamins(that will help)