Don't really have any idea regarding the shingles, but don't discount the apparent nature of the injury. Just the right hit in the right spot can cause a concussion. My daughter's concussion - was from stepping on the end of the big metal arena rake at the barn. You wouldn't think it would have done the damage it did, but it did. Some people (and doctors included) somewhat discounted her issues and/or tried to chalk them up to psychological issues because of the nature of the injury. The fall she took in the shower last weekend appeared far worse - big bump on her head, stitches in her chin - but no new or worsening concussion symptoms. Go figure.

I do wonder if when your body is under stress - from an illness, being run down, overworking, etc - make the length of the PCS issues worse. I have no idea, other's on this board might be able to give you more guidance regarding that issue.

My daughter had a CT and 2 MRI"s that showed nothing out of the ordinary. My understanding is that they usually don't with a concussion. The only benefit from my daughter's imaging is that it gave me piece of mind that there was nothing structurally wrong - like a brain bleed.

Hang in there. Have your niece get lots of rest and no stimulation.