Welcome to YT! Sorry your baby has been scaring you, hopefully it's just hypoglycemia, easily treated. Please be sure to follow the Karo syrup up with some food, as the Karo alone will cause a spike in blood sugar followed by another crash. How old is your baby and how much does she weigh? If she's really tiny and not eating often enough that could be why this is happening. She needs several small meals a day, and definitely make sure she eats well before bedtime. If she continues to have the symptoms, I'd get her vet checked again.
Don't forget to share pictures of your little one
!!!