Headache, chest pain, fainting, dizzyness, lower back pain

I am writing this out of concern for my girlfriend. She has been sick for the past year and has been seeing doctors but none have been able to diagnose her with anything. Her symptoms are as follows:

- Severe Headaches (sharp)
- Chest pain (sharp)
- Fainting (she feels dizzy before hand and almost always feels it coming on); she can't move to fast either otherwise she feels faint
- Dizzyness
- Lower back pain
- Blood occasionally rises to the surface of her skin and she gets red dots that look like bruises across her body
- There are times where she collapses (not fainting) or loses movement in part of her body temporarily
- She has low BP
- Cold sweats when she sleeps
- Temperature is usually around 95 F
- her balance is bad
- She has swollen lymphnodes that seem to be spreading
- Multiple blood tests came back with high white blood cell counts
- Occasional low grade fevers and nausea accompany the above symptoms

This has been bothering her for almost a year now and lately the headaches and chest pain have gotten more severe and she feels dizzy/faint more often. The chest pain and headaches are almost always present and are very painful for her. She's 18 years old, has a really athletic body (field hockey player). She's 5'5" and approx 115 lbs. I'm really hoping someone can help give a little direction as to what her problem might be.