Suggest Treatment For Severe Dandruff

Hello Doctor,I have an issue with dandruff. It is only on the front part of my hair, from the hairline to about 2 inches back, stretching ear to ear. It is very dry, peels in very large layers. It's not itchy. I have very dark hair and even though I do not touch it, pick or scratch it, you can still see the layers lifting off the scalp. I've used all kinds of medicated shampoo from Neutrogena T/Gel, Head and Shoulders, Selsum Blue, and recently Nioxin Scalp Recovery to no avail. I exercise 3-4 days a week, eat a umm well, not exactly balanced, but I eat my veggies daily and fruits maybe twice a week or so, not a fruit person. I drink less than the recommended water a day, maybe a 6oz glass or two daily. But, I can't imagine that being the problem. I'm just annoyed by this, I've been battling this issue since I was 17, now I'm 33. Any advise will help. Thank you for your time.