My gal Brandi suffers from seizure and from what you describe that is probably what it is. In my personal experience if she is stressed it will prolong the seizure. In dealing with her seizures keeping her calm and in a safe, quiet environment is very important during a seizure.
Although Hypoglycemic Shock could also be the cause, but at her age I doubt it. Unless she is very small and has not eaten today.
Take her to the vet as soon as you can!