I haven't thoroughly read through all of the replies so this might be something you have been told about already, but your cat is def. flea infested, and when advantage is applied the fleas are no longer still, they start running around and going nuts, which in turn will cause a cat to act bonkers, can't be still, sleep, twitching,. etc. like mad the first day.
An actual reaction from the med occurs within the first hour usually and def. by the 2nd hour. It looks more like vomiting, very lethargic, they act totally and suddenly sick. Which is pretty uncommon by the way, especially for an adult cat.
An actual reaction from the med occurs within the first hour usually and def. by the 2nd hour. It looks more like vomiting, very lethargic, they act totally and suddenly sick. Which is pretty uncommon by the way, especially for an adult cat.