Mental fog

I have been having periods of mental fog thats taking longer and longer to clear. Dizziness when I lay on my back and look up or if I bend over.I lose my train of thought very easily and have become very forgetful of little things that I should know for example(if someone ask me what meds are you taking, I have to think real hard at that moment and sometimes get back to them). I wake up most the time with a bad headache and have to keep things dim until my BC starts to work. I have a history of untreated anxiety attacks and type 2 diabetes of which I take Metformin 500mg daily.I am so scared about whats going on, please help me understand.