find someone who doesn't live in an old smelly house themselves and see if they smell it. better yet go to their house and see if u smell it there.

i used to think critters were living in my walls, but when mom visited she thought it smelled too (whether same smell unknown). i smelled it even after i moved, but then i do own a smelly dog.

there is an x-ray can be done shows if the sinus air space clogged. try an ent doc. hope u feel better soon.

try a hot shower, sometimes that's the only relief i get all day from headache.