I am having serious hair issues!!?

I have long brunette hair. I have a healthy diet, wash my hair with safe SLS free products, and rarely use heating products on my hair and never color it. My hair is shiny and healthy EVERYWHERE except for my very top layer. I have found out that not only do I have split ends ONLY on the top layer, but the ENTIRE strands of hair are seriously damaged. I have had this problem for about 3 years and im sick of it! I can grow a healthy top layer even when I get it trimmed if its constantly growing back damaged. I really like my long hair and everything is smooth and healthy except my top layer! What options do I have? I cant literally shave my head! help please!!