It does kind of sound like hypoglycemia. Have you ever taken her blood sugar during one of these episodes? If her sugars are low, you need to figure out why they are bottoming out- and an endocrinologist should be able to help you out with that.
Being diabetic and having some experience with low sugars, the more one has low blood sugars the more one kinda gets used to them. I used to know immediately when my sugar was below 70. Now, a lot of times I don’t even realize I’m low until I hit the 40’s. Maybe that’s what’s going on with your daughter and why it’s taking her longer to recover afterwards.
I would talk to your pediatrician and see if you can get a script for a glucose moniter and testing strips. If you can document low sugars, perhaps the endo and peditrician will take you more seriously. Regardless, your pediatrician should be doing everything to try to figure out what’s really going on instead of just telling you to take her to the endo.
Good luck, hope your daughter feels better, and keep us posted!
Martha