This is something that has begun happening to me as well. I was fortunate that I had a few pain-free weeks, but recently little things have been cascading into bad headaches and fatigue as well. For instance, I walked to the supermarket yesterday and felt like I was going to pass out from fatigue, had a horrific headache to go with it. I almost feel like I am slowly regressing at times.

I don't know the reason behind it. My guess is that it is the brain trying to cope with limited resources and getting overwhelmed. Everyone here is right... quiet rest is best. I notice that if I sit at the computer for too long, my head begins to feel heavy on my neck, I get a headache, tinnitus, ear pressure, etc.