Thank you for being pleased my dad stopped having crippling migraines.
No idea about Floo but I know I am. If your dad's migraines were anything like mine then crippling is really the only fitting term. I had the lot - excruciating photosensitivity, aura, fortification patterns,
E. coli-esque vomiting, the works.
Still, horrific as all this was for far too many years, they evaporated spontaneously as they do for many, many sufferers including your dad; and your earlier comment, implying that there was not just a correlation between the local vicar praying for your dad but causation, does raise pertinent questions even for this former sufferer as to why, if petitionary prayer works, God saw fit to cure your dad's migraines but leaves mass hunger, poverty, want, sickness, indeed woe and mischance of all kinds, resolutely and persistently untouched.