I've got the same problem and it drives me crazy.   Sometimes it goes on all day for me if my meds aren't in the right proportions or if I didn't get enough sleep.  I find that if I get some sleep and eat something it helps me recover a little faster.   Maybe you need to up your meds a little more.  Ask your neuro about it.... Brain fog is terribly annoying and exhausting.  I like to call it blender-head, since it feel like my thoughts just went through a blender.   Even people without epilepsy have momments with blender-brain--the most important thing is to realize that it will pass and you just need to relax your mind and let it wander for a bit.  (I'm terrible at the relax part: I should really take my own advice).  I found that once my meds went up the problem got much more managable.  Maybe you could ask your Neuro for some clonazapam or lorazapam (something fast acting) for the really bad days.   But when it does happen, I find that I'm kinda stuck with it for a good fifteen or twenty minutes.  My advice, you can try to focus and work through it, but sometimes it helps to just doodle and daydream and do stupid fun things (buy yourself a slinky).... I play with my daughter's potato head sometimes :).    If your stuck with it, may aswell have fun with it!!!!