How to fix my hair problems?

When ever I comb my hair, play with my hair, wash my hair, dozens of hairs fall everywhere. Sitting at the computer right now, i can scratch my head, and dozens of hairs will fall depending on how vigorously i scratch. How can I fix this? I know it's not normal because my hair line is further back then the normal 16 year old boy (I grow bangs to hide it). Umm.. what else? I dont colour my hair, I do have a lot of dandruff (yes, I do wash my hair with head and shoulders once a week), and my parents dont wanna take me to the doctor because this isn't something life-threatening. This sucks because i've really tried a lot of things to improve my hair and it's been happening for years. Sometimes, my hair doesn't even feel normal, it feels kinda brittle... any solution. What should I try/do?