Nic, I totally sympathise with you. I had a constant headache for about a week and it has finally gone since I started my FSH injections, but comes back occassionally. I'm not keen on taking anything stronger than panadeine, and like you didn't want to get into the habit. The only thing that gave me some relief was to have a lay down in a dark room and try and have a nap. It didn't always work, but I didn't know what else to do.
I think acupuncture could be worth a go. I had my first appt last week and left feeling great. It certainly can't hurt to try it, especially as you are going to be on Synarel for a while longer.
Hope you're feeling better soon.