What To Tell My Boss on Bad Days

Hello. This is my first time posting here. I have a very rare midline brain tumor that resulted in obstructive hydrocephalus. Long story short, the matter of my brain is compressed, which has resulted in executive function problems. I’m working with a psychiatrist and a therapist, but we have not had significant symptom relief yet. The biggest difficulty I have is days when my brain just won’t work with me. I get my work done and meet my deadlines, but our time sheet requires us to explain what we were doing for a total of 8 hours each day. I find I do not have 8 productive hours right now. It’s rare when I do. I struggle every day to justify that time, while becoming more anxious and falling more and more behind on time entry. I just don’t know what to do. Sometimes, I lose whole days to executive dysfunction. If anyone has advice, I would truly appreciate it.