I don't know about the fact that Minnie attacked Baby, but I can tell you that the drowsiness that Baby had was likely related to the Advantage. Unfortunately one of the side effects of exposure to too much Advantage is drowsiness or apathy. This is supposed to go away after a few days.

I am not sure how old Baby is, but it is not recommended to use Advantage on kittens younger than 8 weeks and the dosage should be adjusted for their weight.