Fogging or condensation in headlights is normal, but if its there for days then you have a crack in the housing, the only reason ur having this "fog" is due to moisture in the inside. Sometimes you cant see the water due to it being under the reflector inside the housing.
Remove the headlight bulb from the housing
Remove the headlight assembly from the car and turn it lens down and hold it up, if water is in the housing you will see it.
Check the lens for cracks even small/tiny ones..
Also check the seal, u can as a just incase measure clean the seal and do a coat of sealant over it.