I have a friend with an 8 month old German Shepherd who chases her tail constantly...the dog...not my friend

Anyway, she says she has done this since she was little...they thought it was cute then but now it's extremely annoying because that's all she does...all day...everyday! She has always been crate trained and was recently spayed...she tries to take her for frequent walks to get some of her energy out but it's not helping.
I suggested having a fecal done and maybe some blood work just to be sure everything is o.k. I also suggested checking her food for corn and corn products in case it's allergy related.
Could this be from her being crate trained? Could it be boredom? Could it be OCD? Could it be diet or health related?
I also suggested giving her a Kong while she's in her crate or even while she's at the office with her so she has something to do all the time.
Does anyone have any other thoughts or ideas?