Well, I do have migraines but I had them long before I was dx'd with MS.

Have you talked to your neuro? I think it might depend on where your lesions are. But any headache that lasts that long would certainly be cause for further investigation.

Did they do a CAT scan?

What did they give you for it? When I get one that bad (and thank goodness I don't anymore), Fioricet seems to work, if its a tension headache.

Weather changes? Sinus infection? Could be a lot of things.

I have my migraines under control now with Topamax. So if I do get a headache I know its caused by something I've been doing ... food, stress, allergies, sinus infection, etc.

That's my input for the day...hope it helps!