Sally,
I am so sad that that happened to your son.  You would think that that’s the best place to have a situation like that happen.  Guess not?
If I were in your shoes (and it’s easy to say what you would have done when it wasn’t you and you have the benefit of hindsight), I would have had the doc check his electrolyte and sugar levels.  I have actually passed out before from low blood sugar.  I felt very weak and shakey.  Pending those results, assuming they would have come in quickly, I would have given him something very sugary (sprite) to drink and something salty to eat (pretzel sticks are great and our endo has huge tubs of them) and a triple dose of hydrocortisone.  If he didn’t respond to the oral hc within 30-45 minutes, I would have injected him.  It’s just very sad to hear that your endo- the person you should be able to trust the most seemed to flake out when you needed him the most.  How is your son doing now?  I hope feeling much better.

A PS to my post, Ellie got very bad yesterday and today with her breathing.  She has been to the ER twice in less than 24 hours for high fever (104) and asthma attacks due to her bronchitis.  I think she now has what she needs to get better.  She woke up this morning with diarrhea, high fever and an ear that was draining very smelly fluids.  She said "mom, I feel like I am falling apart and it’s still 2 weeks til I’m 6!  Am I breaking down?"  Poor baby.  She is going to bed tonight feeling better (and probably a bit high from the solu-cortef and albuterol breathing treatments).
Take care
Tonia