Took 40mg 4 days then 50mg 3 days prednisone, going to taper dose down now. have a migraine today, can prednisone at this amount cause migraines?

Not usually: Prednisone can often be used as a therapy for migraines. It isn't clear why you are taking prednisone, nor why you are increasing the dose then tapering, but at least it seems that you have not been on the drug for that long. Prednisone can cause migraines, but that typically occurs when patients are on the drug for either a prolonged time or when overuse has occurred.