Is it possible you are allergic to something in your environment?
At one time I developed an allergy to Tide detergent. Since traces of Tide were in everything we washed, including sheets, T-shirts, etc., I developed a chronic cough. The solution was to shift to a different detergent.
A second thought. You say you are a couch potato. My couch that I sit in to watch TV has what I believe to be a brominated fire retardant in it. I think that all furniture sold today has that chemical in it (to protect us!
) I am allergic to that chemical. I bought a big throw to put over the natural fabric of the couch so that I'm not breathing the traces of that chemical.
A third thought. Yes, going through stress as you have been will definitely affect your immune system.