Do you this this is indicative of MCAS ? I took it in the first year of coming down with me/cfs when I was severe, I also had extreme light sensitivity at the time and couldn't bear to look out a window. Since then I had multiple chemical sensitivity that has gotten worse over the years.
Lately what happens is if im close to crashing or if I'm exposed to certain chemicals, I feel a change in my stomach which feels like tension or anxiety and I also start to bloat up with gas, it happens nearly immediately which is the peculiar thing. I can sense bleach from the other side of the house with the door closed, black mould can give me a prickly throat / fever etc, but the worst one I am still figuring out ( its something in wooden chairs, their cushions or most recently a picture frame, so possibly wood paint ), I've figured out that aside from the stomach thing it also disrupts my nerves in some way, I feel less conscious and my muscles feel twitchy and unprecise, walked into a door frame today because of it.