Hello,
Welcome to the forum. It is nice to know that you are concerned about your GF's health. It is always nice to rule out the common problems that could cause her such symptoms, later suspect serious ailments.
You have not mentioned anything about her medical history, past illness if any, allergy or her menstrual history. It is important to know if she is menstruating normally. If you are sexually active with her and using no protection while sex, find out about her LMP ( last menstrual period ). You may have to consult a gynecologist if she has misses periods. Rule out gastroenteritis
Headaches can result due to problem in vision. You can see an optician/eye specialist and get the eyes checked. Yes, the symptoms that she is showing can also be due to
meningitis ( life threatening disease ). You need to see a general physician.
Meningitis can be caused commonly due to a bacteria called
streptococcus pneumoniae, there are other bacteria/virus that may cause it, it lives in the nose, mouth, etc. It causes infection of the meninges of the brain and get serious ( results in
brain swelling, coma or death) if neglected.
The other symptoms are
stiff neck, fever,
photophobia, seizures, joint pain, swelling, confusion. It is better to get your GF examined clinically and get all the investigations ( CT Scan, spinal tap, X-Ray chest,
blood test,etc ) done to rule out meningitis. She would need hospitalization and immediate IV fluids and care.
Acetaminophen can be of some help but consult a doctor.
Do not lose much time, get her diagnosed with the disease. Have a good day, take care.