Can black mould cause illness?

I have been working in a building for 3 months and after the first week i fell ill. i had a very bad sinusitis infection and a chronic chesty cough. The doctor said my chest was clear. I was ill for 6 weeks. i seemed ok for 3 weeks then my nose started running and a really bad chesty cough now for 3 weeks feeling weak and shivery. The doctor says my chest is clear and no weezing although i do have asthma. i do feel ill. the workplace is in 2 unused rooms covered with black mould and mushrooms growing on it. could this be the cause of my illness. i told the doctor but hes not listening to me. some advice would be more than appreciated. i just want to get better.