Your doctor should contact Allergan to describe where the injections were done on your face, or body, how many units, and other specifics. You should see a neurologist. I'm not sure why your balance is off, nor why you have a headache so long! There can be something completely unrelated as a coincidence that is serious and needs to be diagnosed.
It may be that you had a treatment that left you feeling dysphoric.
These side effects are described. I would recommend contacting your treating physician and let them know you are having an issue. It may be the treatment is causing a muscle imbalance. It may be that you are just very sensitive to the effects of this treatment. If this is the case, allow the current treatment to wear off and then avoid botulinum toxin treatment in the future.
Some patients do get headaches after Botox injections. They usually last a few hours and are relieved by Tylenol or other anti-inflammatory medications. I'm not sure why you were dizzy and passed out. Some people are sensitive to injections/needles in general and may get the sort of reaction you are describing. From my experience, I cannot attribute your problems to the Botox itself. You may want to see your primary care physician for a check up if this...