The exact same thing happened to our little one Skip. He happen to have an episode of hypoglycemia. Because of his small size (1lb @ 8weeks), we should have been feeding him every 2hrs. This was recomemded by the vet.
What dumb parents we were. We only fed him like 3x a day for the fist two days we had him, then on the 3rd day he collapsed
.
He is now shy of 12 weeks and we most definitely keep NutriCal on hand, and are now feeding him every 3hrs.
We make sure he eats well, plays for no more than 20min at a time, and sleeps a lot. Make sure he sleeps.
good luck with your little one. I think our little ones are not to far in age.