Maybe try taking baby aspirin (81 mg) instead. Acetaminophen is harsher for liver than aspirin though. Aspirin does thin the blood so try the baby aspirin. If it helps your headaches it will be safer than regular aspirin.
I read that if you take more than 8 in a 30 day span it wont help you anymore you have to let your system reset. But according to an old guy on doc oz one a day is good bc it's an anti inflammatory. I'm not 100% sure ask your gp maybe? Good luck!
The best thing to take for headaches is Tylenol. If you are getting constant headaches you should she your doctor. I'm not sure about aspirin, but I know Ibuprofen(Advil) if you take everyday you can get rebound headaches. But if you have headaches everyday that you need medication for then you should see your doctor.