There is the possibility of anxiety/stress either one and as far as the breast being swollen that you might want to go get it checked out could be early signs of possible cancer but I could be wrong ...make an appointment and go from there as far as the breast area...everything else has to do with anxiety or stress
Given the fact it's in association with abdominal pain and the time of the year does not really have weather associated with heat exhaustion, I would be concerned about the passing out. The swollen breasts can just be part of her cycle. Abdominal pain could be as simple as she's really backed up and needs fiber or could be sign of a UTI that's turned into a bladder infection or gall stones or ovarian cysts or appendicitis (depending where it's at), and I'm sure there are more possibilities. I would keep an eye on her for tonight but schedule her an appointment for tomorrow. If her pain gets worse or she passes out again, call 911 and get her to the hospital ASAP.