we believe we have a fungus or mold in our infant sons bedroom. the color is a dark brown spot and the the rest of the bedroom is yellow. it almost appears the walls are seeping with yellow. we just bought this house about 16months ago. we painted when we first moved in, the walls were a little yellow, but i thought it was a smokers yellow. since then the yellow has gradually gotten worse and the dark spot came through on the wall. we can not see any place were there is water leaking. it is now turning yellow just ouside the bedroom in the hallway and into the bedroom next to his. we had a mold expert come to our home he says he has never seen anything like this. what should i do? can i just pprimer again with maybe a kilz primer? what kind? should i paint again? water based or oil based? should we replace walls? no one can seem to help us. not even the realitor we bought the house from!