My son bought a home several months ago and immediately after moving in began to notice a very rank smell in the master bedroom. He has had the carpets cleaned, replaced the carpet and pad in the bedroom, replaced the tiolet seals and the smell continues to worsen. he recently isolated the smell to a particular spot on the wall next to the floor. He pulled the carpet back, took off the drywall and found only what appears to be baking soda. There is no evidence of mold or mildew. The smell is so bad that they are unable to stay in that room. Does anyone have any ideas on what this smell might be?