Oh Ellie, I can relate. I've had the never ending headache that not only went on for days but literally months non-stop. I went the route of PT, it did help (along with muscle relaxers and pain killers) although always only temporarily until this last September when I finally (this has been going on for over two years) let the Neuro talk me into trying Topamax (for that and for about the last 6-9 months recurring seizures). I have never been so glad to have gone on medication for anything in my life. I orginially avoided it because I have taken AED's for seizures before and know what they can do to my body and don't want to risk the side effects or long term damage, but finally decided after a bottle of Advil/Excedrin/Tylenol (insert OTC pain killer of choice) a week and no relief for two years I was doing more damage to myself and the pain was unbearable I might as well try it.
Well, that and the fact that the seizures came back. Have you thought that the two may actually be connected? You may be having a change in your seizure frequency or intensity that is causing or presenting itself as headaches. Something you may want to ask your doctor about...
Also, for portable heating pads, most outdoor supply (camping/hunting supply) stores carry small individual heat packs that hunters and campers use that are quite effective some are reusable some are not but that may be another alternative to try also. I loved playing with them when I was a kid, they get really warm.
I hope you get some relief soon.
-Stef