I use K9 Advantix and have never had an issue.
No, you can not apply more before hte month is up and definitely not a different kind
Just got off the phone with my vet and they said its ok. Im starting to think I can't trust them. They gave my puppy his rabies shot when he was 3 months old. I just recently found out that new jersey state law sais you can't give them rabies shot until 4 months. When I asked them about it they told me he was almost old enough.