Mold behind the wall

Several months ago I told my landlord that my bedroom closet smelled really bad, I completely cleaned out the closet and the landlord came over and checked it out. He said there was no smell and that there was no mold. The smell got so bad that I closed and taped the door shut. Yesterday the closet got brought up again, and he told me to leave the door open and that the smell would go away. Today a mold company come over and checked the closet. They found 3 different sources that could be where the mold is coming from. One is a leak from the roof in the corner, second could be from where there used to be a vent of some kind, and they are worried about what is under the carpet. I never had a chance to let the landlord know that they where coming to check, as he hasn't been home and has no cell phone. The company said that when they come across a problem like this where the mold is behind the dry wall that the landlord will not fix the problem. When I bring this all up to the landlord again and the fact that mold has been found what are my next steps?