Carol Clement
I have 2 suggestions. One, look for sources of mold in your house, esp your basement. If so, be aggressive about throwing carpet, boxes etc out and wipe up the floors with Top Job or something strong and leave fans and other ventilation on for awhile. Then get rid of the source of dampness. 2nd suggestion-Beware of the rebound effect of medicine. Taking medicine for headaches every day or most days causes headaches. Then it becomes a chronic cycle. I've also heard of a fungus in your nasal/lung passage that could be causing chronic headaches. I find that in the winter that keeping hot water vaporizers running clean and running whenever the heat is on is enormously helpful. Good luck. You need to be a detective and find the source.