Multiple Chemical Sensitivity is the base illness for 
Electromagnetic Hypersensitivity (EHS). Those with MCS may or may not have the EHS component. Many time the person with MCS can remember the smell of the overpowering chemical exposure that initiated their illness. Something triggers in the person so they become super sensitive to everything, including natural body odors from their own body.
I remember thinking something must be wrong with me since no deodorant was strong enough to eliminate my odors. I was incredibly embarrassed to be in public just to get my groceries because it smelled so bad, but after I was told by several people that I smelled fine I was able to relax and realize it was my sensitive nose.
I use to enjoy flowers, but after a day roses smell putrid as if they had been rotting for a week.
You become the canary in the mine… which at times is a blessing. Once on a family trip the car was having problems. I picked it up 20 minutes before something actually happened and it would have been great if the family believed me instead of just dismissing it to my sensitive nose. We may have been able to repair it before it became a major issue.
There are huge ramifications in every sense of the body. You may hear things that are beyond normal human range like dog whistles, pest control devices, the lights, or things like the trees conversing. You are not crazy.
You may see things that are beyond normal human range, like spirits, Schumann lines, the veil between earth and heaven. You are not crazy.
You may smell things that others aren’t smelling, like honeysuckle in winter or your own body odor. You are not crazy.
You may feel things when there is nothing there, like bugs crawling on or under the skin. You are not crazy.
You are hypersensitive person…not those defined as worriers, but those who have extraordinary senses- either born with them or caused by exposure. You have the ability to be extremely empathetic and fit the profile of the adviser which makes up about 20% of the world. There are benefits with having this curse. One book that helped me was called the Highly Sensitive Person by Elaine Aron.