I Always Feel Very Tired And Fatigue For More Than

I always feel very tired and fatigue for more than 10 years and headeachs.
i did hundreds of blood tests, ct scans and xrays, all i find is that my red blood count is a little bit hight.
The hematologist couldn't know the cause, he told me you can donate blood.
i take high blood pressure medicine 5mg, advil and motrin.
i can't think clearly and always have a brain fog.
Can you help me?