Answer #2... tap water is fine for generating humidity; think "slow simmer" rather than boil. Or, if the heating system is on, there are ways of using a tray of water, a small stand (stool or such), and a towel.
Does it make any difference what time of year you go?
Does it matter if you stay in a hotel or in the house?
What other "differences" have you tried or noticed?
I'd be very wary of moving into an area that causes me that much problem... without at least knowing what the trigger is and what can be done about it.
