the same thing happens to me with exercise. one time i was doing yoga in a heated room and could feel myself losing my grip. i got super irritable and couldn't focus. i finally put 2 and 2 together and left the room, went home, and got something to eat. but i was shaky for a day or two. i think when you crash with the combination of exercise, it takes longer to level out.

the only thing i've realized is that it's all about the daily maintenance of diet. the more you stick to the low carb diet, the better your chances of recovering from a crash quickly. i no longer eat any fast acting carbs whatsover and also caffeine is a big one for me to stay away from. also, be sure you eat a meal or snack when you crash like nuts with cheese or something like that, not juice or sugar.