Buspar (buspirone) can cause involuntary facial movements? Its happening to me since iniciating the treatment a month and can't see my doctor in at least 3 weeks

Yes, but unlikely. The incidence of abnormal involuntary movements from Buspar (buspirone) is very small. It is more likely that your anxiety (which is probably why your doctor is treating you with buspar) is prompting you to be extra sensitive about this concern. You can certainly stop taking Buspar (buspirone) until you next see your doctor and discuss the concern with him or her at your next appointment.
Buspar (buspirone) Possible. Recommend either tapering the dose by half if taken twice or 3x daily, or splitting the daily dose into twice or 3x daily if taken once a day, until u see your doctor. Ofcourse, leave the office a message that u r doing that.