Girlfriend had neck popped by chiro. now has terrible headache, neck stiffness, nausea and numbness in fingers. no fever. what should she do?

Depends on severity: If symptoms are severe or moderately severe, the usual recommendation is to call 911 for an ambulance. The paramedics can put a rigid cervical collar on her neck to safely take her to the ER for evaluation. Going by ambulance is safest when a person has had rapid neck movement followed by nerve symptoms, such as in a football injury, riding a bike into a tree, whiplash from a fender bender, etc...