Are Headache,dizziness,nausea And Fatigue Symptoms Of Pregnancy Or Concussion?

my girlfriend thinks she is having early pregnancy symptoms. (Headache, dizzy, nausea and vomiting, fatigue) However she recently had a concussion about 2 weeks ago. Then on Wednesday of this week she hit her head again and today she is experiencing these symptoms i listed above. Could these symptoms be from her concussion, or is she pregnant?