Fatigue,Head Pressure and Brain/Mental Fog?

Fot the last past month I been having daily brain fog,I feel spaced oy like Im not here and sometimes a little mental confusion.I have slowed speech like I cant talk right.I get extremely fatigue/exhausted all day even though I sleep 8-9 hours a night.I also get pressure headaches.I been to the doc and he basically thinks it anxiety/depression whic I do not agree!! I cant think right any more and I am tired all day and I am only 21 witha 6 year old to take care of.I have been tested for lyme,lupus,thyroid,diabetes,anemia had a soine mri and a ct pf the brain and sinuses and nothing came back.What could it be?