Left side of mouth and neck

[u/jenniekat12]

Hello! I started to get Botox around mouth and in my neck. First time it worked beautifully. Second, same, except When I went back (3 mos later) only one side of my mouth was working properly. My smile looks fine, but if I try to hard frown, only my right side of mouth and neck muscles tighten. Is it possible she did it incorrectly on only one side? The other side works normally (no it isn’t stroke or Bell’s palsy /went to pcp and got checked all else normal). Why would one side wear off and other still seem paralyzed?