Vectra 3D is made by Hartz and sold exclusively thorough Banfield. Both those names raise red flags for me.
Vectra 3D contains permethrin which has serious known side effects. I am no vet, but it sure sounds like symptoms of permethrin toxicity to me:
Overdose/Toxicity
May see drooling, vomiting, diarrhea, incoordination, increased excitability, seizures, or change in body temperature (higher or lower). The Use of Permethrin (Bio Spot-Spot On for Dogs, K9 Advantix) http://www.yorkietalk.com/forums/yor...ea-tick-2.html