Botox can correct facial asymmetry or sometimes cause it if injected improperly. The injections should wear off within the next few weeks and there really is nothing more to do right now. I would consult with a cosmetic dermatologist for your next treatment to ensure the best cosmetic results.
I agree with Dr. Blinski -- the asymmetry is not obvious in the photo. Generally, if patients get a crooked smile from Botox, it occurs when the injections around the eye are place too low, too medial, or too deep. This should wear off in a couple weeks. Please follow up with your doctor.
In posted photo I do not see any real facial animation deformity. If only 50 units total injected in both masseter muscles (jaw muscles) than the dose was very low and metabolism off the BOTOX would occur quickly. Best to seek in person second opinions. Follow up would be nice.