What Causes Pain In The Middle Of The Chest?

HI my daughter is ten years old, healthy and very active, yesterday the school nurse called to let me know that my daughter was having chest pains. The nurse informed me that she checked her oxygen and heartbeat and that everything looked fine. My daughter told me that this sharp pain, right in the middle of her chest, began after she was outside at recess, doing little activity; swinging on swings, when she came back into the classroom she felt her chest heavy and the pains started, so she went to take a drink of water (room temperature). This only made it worse and that is when she went to the nurse. I had her rest yesterday, and every so often she would say that her chest was hurting her. Other than that she was her normal self. This morning I had her stay home from school so I can keep an eye on her. So far she has been fine, only when she is in movement with deep breaths she complains saying, "ouch, my chest". I'm back and forth on what may be causing this and if I should be rushing her to the clinic. She seems ok in all other aspects. I will let you know that asthma runs in our family, my grandmother and brother have severe asthma and i, myself have mild. Listening to her, I don't see or hear the symptoms of it. Is there anything that I should be doing to make her feel more comfortable? or should I take her in for a check-up? Being mid-Friday afternoon she will not be seen by her family physician, I would have to take her into a small emergency medical clinic. Any advice? Thank you.