So, i figure you are about 4-5 months post op. Congratulations for your determination! You are working some long days.
I found the need to have a break midway through my day at that point. Can you close your eyes and get an auditory/visual escape for 15-20 minutes each day? The break or "catnap" might help with the headache, too. The theory is that the nerves need a brief rest. Forgetting items that are not written down is common post op.
Having 90% balance at this point is great! So that part of your recovery is a positive. Your energy level and ability to focus will improve as the months go by. I can honestly say that my energy levels weren't back to normal until the 11th or 12th month. Now at 27 months post op I have a feeling of complete mind and body recovery. My point is that you keep getting better.
A visit with your doctor might explain the reason for the diminishing hearing. Perhaps the nerve response is the reason for some of the fatigue now.