Hi - I was interested to see your post - tho sorry you have to deal with this. I have tension type headaches frequently and can't take most OTC pain meds because I'm allergic to them. Problem is, the tension headaches can morph into a migraine if I don't deal with them.
I don't know if you get migraines as well, but latest thinking is that stress is not a trigger for migraine exactly, but makes us more vulnerable to other triggers. I know for me, I will get a migraine where the only thing I'm aware of is the stress - and usually the tension headache first. The best thing I've found is to practice regular deep breathing and relaxation techniques. I'm writing more about that at my blog: www.meganoltmanfreemybrain.typepad.com if you want to read it. I worked with Dr. Ian Livingstone - the neurologist who wrote "Breaking the Headache Cycle" - another really good book and it has lots of relaxation techniques in it.
Good luck to you!