How To Treat Dizziness,headache And Fluttering Sensation In Chest After Workout?

My granddaughter is 21.She has been working out at the gym and eating a low fat diet. Today during her workout, she experienced dizziness and did not feel well. She had a very bad headache. She took two advil and came home and went to bed to rest. She seemed to feel better and had dinner with us. Just now, she came to me concerned because she is feeling an unusual sensation in her chest, like a fluttering. I am not sure whether we should be taking her to the hospital. What might be the cause of these symptoms.