We've lived in our town home for about 15 years and we haven't had any leaks or water damage. Mysteriously since about 4 weeks ago there's been this strong musty moldy smell in the den which is at the entry level of our townhome. We've had 4 different people check for mold, and every single person has said we don't have mold. We got the ducts cleaned, and the smell persisted. We finally found a small patch of mold on the cement floor near our HVAC unit, under some loose flooring which we then got professionally remediated. The weird thing is that the smell still persists. Any ideas why this might be continuing to happen? Also the smell gets intense from early evening/nightfall, and by morning it's almost non-existent. We're also in the process of getting air quality testing done so we'll know definitively whether we have mold and it's just invisible to us for now. Thanks for any input on this.