Hello. The swelling and the pain is due to Exercise-induced compartment syndrome. This is due to a pressure build-up within the muscles. Muscles are enclosed within a tight tissue called a fascia. This fascia wraps around and contains the muscle. Normally, the fascia has enough extra room within to allow the muscle to function without problem. When activity levels are increased, blood flow to a muscle increases, and the size of the muscle increases. In most people, the fascia allows sufficient room to accommodate this increase in muscle size during exercise. However, in patients with exercise-induced compartment syndrome, the fascia is too tight, and it constricts the muscle during activity. A period of rest may be attempted, as well as avoiding any activities that causes the symptoms. If the problem re occurs again, she may need surgery to release the fascia provided exercise is vital for her. Thus she does not need any emergency care now. Hope this helps. Please write back for further queries. Wishing you good health.