Contact the local health department and tell them that you have a possible mold issue. I am pretty sure they may respond, being that your apartment may not be the only one effected.
I am pretty sure they may repond just like if there is a complaint against a restaurant.
Keep us posted and what remedy you end up with.
Years ago, while attending school, my neighbor and my wife and I just got up and moved out of an apartment complex because the landlord became a crackhead and gangbangers started moving in. This was a health and safety issue and a landlord has the obligation to provide security to their tenants. I believe this may be at the same level.
If mold spores get into your child's chest, this may become a serious health issue..