I have an update.
After 8 nights of sleeping in the living room, I  noticed I was still waking up sick and getting better after going  outside. I started sleeping on an air mattress on the balcony (which has  a roof but no walls.) And I immediately started feeling much better. I  had developed severe shortness of breath, especially while climbing  stairs. I had to stop and rest halfway up the long stairway that leads  from the street where I catch public transportation and my apartment  building, which is on a hill. The shortness of breath resolved almost  immediately.
Movers came August 5 and carted away most of my  stuff. On the night of August 6 I took an overnight bus to Boston, and  later on August 7 I went to Harrisburg to stay with relatives.
I  should have taken my respirator with me. I woke up feeling ill on August  8, and had increased neuropathy in my fingers and toes. I began  sleeping in a newer part of the house that's over a crawl space and not  my cousin's admittedly moldy basement. I got another respirator and  started wearing it most of the time I was inside. The room I was  sleeping in had windows on three sides. I opened all of them and ran the  ceiling fan. 
The bathroom next to that room had three "air  fresheners" in the tightly closed window. Smelling that odor made me  feel ill. When the basement door was open I'd smell a strong smell of  pesticides. 
My cousin and her husband were very cooperative in  trying to make their house livable for me. My best days were days we  stayed away from the house the longest.
I went back to  Philadelphia on August 15 and spent two nights there. I was having some  symptoms, so I went looking for mold, and found a contaminated rubber  bathmat in the bathroom next to the room I was sleeping in. It looked OK  on top, but it had a luxuriant growth of black mold underneath it. I  put on my respirator, disposed of the mat, and scrubbed the tub and tub  surround.
Then I went to the Jersey shore. No noticeable mold,  but workers were out on the beach constructing a handicap ramp and doing  other work. I kept catching whiffs of diesel fumes. I still had some  mild symptoms.
Then I found out about "Multiple Chemical  Sensitivity." I've gotten contact dermatitis from various things (mostly  cosmetics and sunscreen) since I was a teenager. When I was 23 I  learned I was allergic to mold. I figured out in my early 50s that I  can't be around chlorine or even come into prolonged contact with fabric  that's been washed with chlorine bleach. I get hives, rashes, and  weird-looking blotches on my skin. During a cleanup operation after a  basement flood, I found out I also react to the spray-on antifungal they  used to prevent mold growth.
Cologne, perfume, and other scented  things can make me feel ill. Plug-in "air fresheners" and scented  laundry products can give me headaches or migraines. I always use  unscented laundry detergent, hand cleaner, hand lotion, and body wash.  Recently I noticed burning and tingling in my hands and feet when I'm  exposed to diesel fumes.
If you have an hour, watch this video  about MCS. I'm not nearly as disabled as most of the people in the  movie, but I'm getting more and more sensitive. It's possible that many  of the symptoms I've been attributing to Herceptin (runny nose) or chemo  (respiratory problems, shortness of breath, light headedness, skin  problems, GERD) are caused or exacerbated by MCS.  
https://www.youtube.com/watch?v=aJuB...ature=youtu.be
Now that I've figured this out, I can take steps to limit or avoid exposure. 
You might want to go fragrance-free now.
Amy