Zizar,

What have you done for treatments, therapies?

Brain fog for me is generally indicative of inflammation and/or oxidation. A clean diet is helpful along with added supplements.

Fish oil is tremendous for decreasing brain inflammation and regenerating. Not a cure all but nice to have. Check out Mark's post pinned at the top of this group:
"Vitamin and Supplements Regimen"

Dr. Michael Lewis has this omega 3/fish oil protocol:

The Omega-3 Protocol for Brain Health – Brain Health Education and Research Institute

Your nausea may be related to vestibular system injury. It may be helpful to get help from a physical therapist trained in vestibular system rehabilitation.