Hi MVD,
I have also been dealing with the same issue. My headaches actually started about two years before my surgery. I can even remember the specific day I got the headache and it never -quite- went away. It was all over my head but much more intense on the tumor side. Now, three years after my translab surgery, I still have the same headaches. I've tried taking different pain killers including antidepressants and even migraine meds (I believe I get periodic migraines as well as the AN headeaches, 2-4 times a month). Nothing has worked for me except for Prednisone, which is a very bad drug to be on long term.
My headaches also intensify often with increased activity. When they are really severe, I can barely move my head without making it pound.
In addition to the drugs, I've tried several other things. I took 500-1000mg a day of niacin for a while, and that seemed to help, but when I went off of it, I didn't really notice a difference. I've also tried taking hot showers or baths, and that seemed to help them subside temporarily. What used to work quite well would be to take a hot bath, 800mg of Advil, and a cup of coffee (for the caffeine), then rest. It's not working so well anymore though.
Tylenol doesn't work very well for me for some reason. Advil is what generally works the best. For OTC meds, I've also tried Excedrine, Aspirin, and Aleve (naproxen) but they don't help much. Like your worries with Tylenol, I'm worried about the long term effect of Advil, especially because I take large doses. It's know to cause ulcers and stomach bleeding.
I think the best thing that works for me as preventative is a healthy lifestyle. Meaning, lots of healthy food, low sodium, regular aerobic exercise, and keeping stress at a minimum.
I haven't actually tried medical marijuana, although someone told me I should.
Anyway, I guess I don't have some "great" advice, but I just wanted to share my experience. We're all in this together! And don't give up trying. You never know when you might find that one thing that works for you.