Sharp Pain And Swelling In Upper Abdomen

Hi, My wife and I were running and she had to stop because she started to experience a sharp pain in the mid-left of her upper abdomen. This has happened to her before without any physical activity. It causes her pain when she breathes. She also believes that her stomach is swollen. We are thinking of going to see a doctor today, but any helpful ideas you can give as to what is causing this would be appreciated. Thank you Nick