I lost my husband a little over 2 months ago, and I feel the same way. My brain is foggy, heavy, and thoughts move slowly. It's a chore to do or plan anything. I misplace things and can't find them later. Lately I was starting to worry that maybe it's the first signs of a brain problem. So it's comforting to know that others have similar symptoms, and that it's a natural part of the grieving process.
Sometimes I get an overwhelming feeling of fear and panic, but I know this is also part of the process. Doing breathing exercises helps me get through those dark moments.
I've been reading a book that has helped me understand the neurological components of grief and the grieving process. It's called The Grieving Brain by Mary-Frances O’Connor. It doesn't stop the pain, but at least I can now understand why I feel this way.
Wishing you strength and peace during this overwhelmingly painful journey.