This sounds pretty serious. Have you consulted a Dr. about this? If it is hypoglycemia, she will need complex (high fiber) carbs and protein. This combo breaks down slower and is good for maintaining energy. I am type 1 and a road cycler and racer. We call a hypo attack a "bonk" and it is common even with non-diabetics.
this happened to me exactly. i too suspect that the adrenaline and the desire to win made me almost crash at the end. in fact i cannot remember the last 3 miles of the race, all i know is that i finished. i went to doctor after a few days and my liver enzymes were very elevated, however no sign of infection (hepatitis, mono, etc).
it's been a few weeks from the event and still cannot say i feel 100% recovered, i am kind of afraid to run, and in competitive races i believe i'd make a mistake to participate again.
i am 40, male, so there are obvious differences, but the story is 100% similar.
as for the diet, i was 90% vegan (no animal products), now i have a bad craving for oatmeal, so perhaps i did not have enough carbs in my body.
i really don't know...
My daughter was diagnosed as severely hypoglycemic and also is 17 and a cross country runner. We had repeated episodes just as you described. Even with the proteins, we were not able to get her regulated. The adrenaline that comes with the race seems to make it so she can't keep the blood sugar regulated. We finally ended up with a paramedic having to treat her at the state cross country meet. After talking with the doctor, we decided that cross country was just too much for her. Non-competitive running seems to not be a problem, but the competition and the adrenaline is a problem. She runs track - since the races don't seem to bother her the way the cross country meets do.
I understand what you are going through. I read your post and thought I had wrote it last year.
Your description does sound to me (a long-time type 1 diabetic) to be very much like symptoms of severe hypoglycemia. If she feels bad after she runs despite the diet with low glycemic index foods, you may want to keep some Gatorade handy for her to sip immediately after a run. Or even give her a cup somewhere in the middle of the run if she is allowed to drink something. Gatorade is absorbed by the body quicker than orange juice and while I wouldn't think she should drink lots of this very high-glycemic drink, it may be exactly what she needs to recover after very strenuous exercise. Just a cup may make her feel better and may prevent the worse symptoms from happening.
Lots of people seem to have problems with hypoglycemia. If this only happens to her when she runs, you may consider making sure she eats plenty of proteins in her last meal before the event to carry her over until it is done. Proteins seem to be very helpful to hypoglycemic people.