Mycotoxicosis
Sorry for the wait in my reply Goldy.
The disease I am refering to is mycotoxicosis. It is caused by the ingestion of mold or its spores be it by mouth, skin, or airways. Remember recently the dog food cases where several dogs became sick and died, that is one representation of mycotoxicosis.
It would take a lot of space to fully explain here this disease and its process so I will try to make my point short:
Mold is bad, and not just because it doesn't smell good and destroys things. Even in the Bible (whether you believe in it or not, that is irrelevant here) there are very specific ways of dealing with household molds. Why? It can shut down the entire body in its worst case scenario which can lead to death. It can cause respiratory distress, fevers, coughing, sinus problems, allergies...the list goes on. The typical belief is that it only attacks the immunocompromised, elderly, and babies, but this simply is not true. It's only true in the fact that these classes of people will generally fall ill first. A typically normal and healthy adult can become sick just as in the case of a cold. As for the young lady I referenced in my first response, she was not immunocompromised, somehow she inhaled enough mold and it colonized in either her bronchus or lungs and it gained entry to her blood stream and the toxins produced by the mold shut down all her organs. When she first became sick and went to her doctor for a productive cough it was diagnosed as bronchitis and treated with an antibiotic, a typical and reasonable diagnosis and treatment for the history she gave and symptoms. Unfortunately antibiotics don't kill a mold, antifungals do. Within a few days she went into respiratory distress, was admitted to a hospital and was placed on a ventilator. Sometimes it's too late to combat an infection. And this was that kind of case.
Don't think I'm ringing the doomsday bell, but be aware of your family's health and the exposure time...if this is indeed a mold. If a family member becomes ill with anything see a doctor promptly and explain what's going on in your house, give him/her the information they need to make an appropriate and diagnosis and treatment.
I haven't read every reply but it may perhaps be time to start looking for leaks in the roof that may be causing water to run down a wall. Or condensation collecting from an uninsulated air conditioning duct and collecting on wall or ceiling insulation. Unfortunately, insulation will hide a leak for years because there's just enough moisture to create a breeding ground but not enough to damage drywall thus making it extremely difficult to pinpoint the location of this issue. I would try to start thinking outside the box.
Also if you desire more information on mycotoxicosis, the internet, library, or doctor is your best resource.
Good luck to you and your family!