What Causes Dizziness And Nausea After Exercising?

My girlfriend was doing some exercises and started complaining that she was feeling light headed. Immediately after the tingling began she felt nauseous. She never actually vomited. but the nausea escalated to gagging. She began feeling warm then cold. She was sweating and felt cold and clammy to the touch. She never lost consciousness but says that her vision became pixelated and went orange, to red, to black very quickly. Her breathing was laboured and sounded raspy. She s been eating well and getting all the nutrients she requires and she s had regular bowel movements. She feels better now, still queezy but the dizzyness has subsided. It lasted for a few minutes, no more than 4 minutes. And I m writing this almost 20 minutes after the incident. She is phobic about doctors and hospitals so I am asking for help in trying to diagnose this for her. Obviously I am concerned and would rather her see a doctor but that it out of the question. Anything you can suggest would be helpful. Even just some ideas as to what we could be dealing with. She is educated in homeopathic remedies if you are able to suggest some things she could try. Regards, Michael