What Causes Extreme Fatigue And Dizziness?

This is so not me, I am not feeling right, I am always fatiqued, I lost interest in things I used to enjoy, I started to blame this on my age, but somehow it all doesn t make sense to me. coworkers told me to try Vitamin D, Probiotics and so on, but it seems to me its not helping. I actually start to asking me, is this what it means getting old? I do have migraines for a long time and its somehow controlled, I do experience sometimes dizzy spells which occur out of the blue. the worst is the loss of interest in things and fatique