mold is hard to get rid of
it sends fibers through the material that you may not be able to see
that's why you can't just cut it off of food and eat it {think cheese and bread}
the first thing is to fix whatever leak there is
the second thing is to remove all affected material i.e. drywall,wood, anything porous
third i would google pro level mold remediation chemicals
look for products that are anti-fungal
you got any pics of the affected area
also you should wear protective clothes and at least a very good face mask when removing mold
a respirator is better
i do home repairs/remodels so you can hit me for advice