The best thing to do with significant mould contamination is to hire a professional because it's not what you see that is making you sick, It's what you can't see. The standard for do-it-yourself mould removal -- with proper attire, respirator, and preparation -- is one square foot, not 4 x 8 square feet. Remember that that you must contain the mould and remove the mould completely.
If you see mould on any interior walls, fully assess the condition of the wall and the extent to which the mould has taken over. If the plaster has been compromised, is crumbling or bowed out and covered with black or bluish splotches, it will need to be replaced - it is not possible to eliminate mould from inside the plaster itself.
If the wall is structurally sound but still covered with mould, you may potentially be able to remove the mould spots with a proper mould cleaner and some scrubbing.
However, some mould is better off remediated by professionals because it may be harmful when present in large amounts.