Without photos or knowledge of the dose and location it is difficult to give an accurate diagnosis and recommendation. With that in mind, from your description it sounds like the target was the DAO (depressor angular oris). This is the muscle that pulls the corner of your mouth down with frowning, or making a sad face. Off label Botox injections into this muscle can give a slight raise to the corners of a downturned mouth at rest. Some injectors target this muscle close to the bottom edge of the jaw, we prefer a slightly higher and more lateral point for targeting the DAOs. In our experience the injection point along the jawline has a higher incidence of weakening the depressor labii inferioris in addition to the DAO. This muscle pulls down the lateral portion of the lower lip. If Botox spreads to this muscle on one side and not the other, the smile will be crooked. The side that is lower with animation is the side with function, the weaker muscle will not pull the lower lip down as well and that side will be higher.If you try and bare your lower teeth and the lower lip pulls down unevenly this is most likely what happened.This asymmetry will start to improve in 4-6 weeks, but may take 2-4 months to completely resolve. One option is to have a small amount of Botox injected into the depressor labii inferioris on the side that is lower with smiling or baring your bottom teeth. You will not have as much lower teeth show with smiling when both sides are weakened but, the smile will be more symmetric.You should make an appointment with your doctor, get an exam and discuss options.