I usually say that in any field of medicine, anything can and does happen. Nonetheless, I have not seen this occur. I have seen Botox make incredible improvements in people's lives and people who used to live in pain live pain free after Botox treatment.
Botox can be caused by external triggers in the base of the neck, forehead, or nose. This can be relaxed with Botox or with migraine surgery. Internal triggers (inside the brain) cannot be treated with Botox or surgery and need medical therapy with a Board Certified Neurologist.
Discuss this with your neuorologist. Migraines associated with hormonal changes may not be helped from neuromodulators like Botox.
Botox is now FDA approved for migraine treatment. I do find that my patients who suffer from migraines tend to get a headache after injection that may last several days. Typically this is a dull, aching pain and not a true migraine. Most patients say it is "annoying" and not truly painful. It depends on where your migraines start and end where the injection should be placed. Typically there is significant relief that lasts 3-4 months. Good luck!