I have problems with sleep from a brain injury. it has gotten better over the years but when it first started I had problems similar to yours though not at extreme. I've never heard of a flue virus affecting the nervous system and I think the pet scan is a good idea. I don't remember if you have taken prescription drugs to help you sleep. I'm glad you got some sleep last night. keep us posted. also you might want to throw this question to mark in Idaho in the brain injury room. he knows a ton of information and might be able to help. try not to be scared and don't lose hope