For the past two weeks my husband and I have been smelling a strange smell in our family room. While investigating where the smell was coming from, we came across a horrible smell when we removed the electrical outlet cover. The smell has a earthy damp stench that's quite sickening. We have moved all the furniture out of this room and have covered the room opening with plastic as we are not wanting this smell to spread throughout the house when the furnace comes on.

Now here is the dilemma we called a "Mold company" who came today and the employee stated that he has never smelled this kind of smell before, I found this bizarre as referencing from google they describe black mold smelling like " damp earth smell." he took a moisture test and there was nothing. Money was charged and then he left. So later that day my husband and I opened up a part of the wall. Well surprise, behind the wall was black mold underneath the insulation on the OSB. My concern is we have no idea where this moisture is coming from. In anyone's experience, can anyone tell me who am I supposed to call if we have a moisture issue causing mold, but we our unable to figure out what has caused this. Thankyou for any help.

See picture down below.