I have MCS and find the exact same problem with living spaces. People have no idea how much damage their chemicals and cleaning methods do to people like us. I had trouble with a smoker in a previous aparment, who was smoking more than just cigarettes. Even with my door shut, air purifier on, window open with fan, and door seem covered, I could not keep the smoke out. When I did land in the ER for chest issues and a sky-high d-dimer, I contacted the landlord and he told me I needed to find another place to live.
When I'm exposed to mold, formaldehyde (on new clothing, in stores, etc.) chemicals, mercury (dental offices), pesticides, fertilizers, or cigarette smoke on people, I immediately get a tight chest, my breathing becomes labored and painful for a day or so, and I feel it doing immediate neurological damage. I have been exposed to so many neurotoxins from Lyme, mold, pesticides, heavy metals, etc. that my BBB is damaged and not able to fully protect me.
What your condo guys did in cleaning the carpets and turning the A/C off is a recipe for mold! Mold produces neurotoxins. Depending on the type of mold, brain damage can be done.
Have you ever been tested for mycoplasma pnemoniae or chlamydia pnemoniae? From what I understand, if the mycoplasma or chlamydia is treated, there's substantial improvement in respiratory symptoms.
I have the mycoplasma, and have not yet treated it because I'm treating my candida and leaky gut right now (it's totally out of hand). My nutritionist tells me that there is a strong connection between leaky gut and MCS, and that MCS often improves when leaky gut is addressed.
I hope you feel better!