What is making me sick? air conditioning? mold?

my husband, cats, and i recently moved into another apartment up north. when we turn the a/c on we all get sick. nose bleeds, chronic sore throats, constant sinus drainage. i'm also exhausted and running a temperature. we were wondering what it could be? do we need to just buy a humidifier because the air is too dry? i'm 6 mos. pregnant and want to make sure it isn't anything life threatening. any ideas? thanks