Re: child with cronic cough only at home
No, your assumption about the allergic cough lasting past being in the house is wrong. I am allergic to a common product used with floor cleaning machines. I can walk into a store and start coughing and stop almost the moment I walk out. Then I know it's the place and not me.
As someone who has fought allergies all her life including over 40 drug allergies and anaphylaxis, allergies still surprise me. So yes, it could be something that came into the house 3 months ago and is still there. Something as simple as a new floor cleaner. Have you changed any cleaning products? A new air freshener? A new plant?
Kids can have a psychological cause for a cough but I bet you it's something small and insignificant that changed in the house and she allergic to it.
BTW, we continue to develop allergies all our lives so tests done a couple of years ago measured only what she had developed an allergy to as of that day...not what was to come.
And some allergies can come and go. If you are allergic to bee stings you can lose your sensitivity by up to 20%/year that you aren't stung so after as little as 5 years, you are no longer allergic....until you get stung again. The first sting is minor but goes up with each sting until you get highly allergic and then you have to carry an Epi-pen again until you go without the stings for a while.
Good luck trying to figure out what is causing the cough.