Cognition and Vision Problems: Feeling in a Fog

I have been experiencing the following symptoms for almost a year and a half and have not gotten any diagnoses from doctors:
-feeling very "out of it" or constantly in a fog (feeling you might get after staying up for 2 days straight)
-problems with short term memory and concentration
-field of vision seems to be blurry, see gray spots sometimes; light seems to make this worse
-not being able to think logically or make associations
-generally not feeling like myself, having strange thoughts


Most of these symptoms began rapidly, I remember the day of their onset.  I tend to feel a bit better at night (more clear headed), usually right before bed.  Also have very small windows once a week or so when I feel a bit better for about 10 minutes or so.  But overall, these symptoms persist through most of my day.

I have had a sleep study where everything came back normal. Tests for mono, lymes, thyroid came back normal as well. Doctors suggested depression and anxiety as the cause, and I have been on two different anti-depressants with little success.  I didn't have much stress or anything traumatic happen prior to onset, and have little history of depression/anxiety in the family.

Has anyone had a similar experience or any ideas of other things that might be causing this?  Thanks.