I have so much sympathy for this experience. I think allergy pills are a good bet. When I get multi-day headaches, even if it's not allergies, at least a benadryl will knock me out a little.

I've had a lot of these in recent months. My dad suggested I might be having cluster migraines. Fun. http://en.wikipedia.org/wiki/Cluster_headache

I hope you're feeling better soon. Let me know if you need anything. I can swing by after work.