I used to feel this. I would get dizzy and would make mistakes in work and couldn't think straight. I had brain fog and everyone in work said I looked confused.
The tablet at different doses effect different chemicals. When I was on 75mg and 150mg I remember the TV or PC monitor would make me feel dizzy like my eyes couldn't handle bright lights, or I was that drowsy I had to take a nap away from the computer and couldn't focus on a certain task for more than 30 mins.
I went from 150mg to 225 and it has helped. I have trouble with memory and I have ED but the brain fog seems alot less.
try going to 225 or 300mg for a few month and see how it goes.
If nothing changes or is worse when you have tried the higher dose then try a different tablet.
Everyone is different and everyone wont get the same results from the same medication.