You might want to look into methylation cycle genetic variant testing, and start getting supplemental Vitamin B12 to help support the methylation cycle. Multiple Chemical Sensitivities (MCS) can sometimes be caused by inadequate enzyme function in the liver and mitochondria, which may explain why you feel as if you have Asthma even though tests are negative for Asthma. Also, magnesium is involved in over 300 enzymes in the body (some of which are in the methylation cycle), and the typical Western diet is woefully deficient in magnesium. Other vitamin and mineral deficiencies or imbalances may also be contributing to your situation.
I'd also suggest considering eating as much organic as possible to avoid genetically engineered (GE) foods. GE foods have been strongly correlated with an increase in the development of and severity of allergic reactions to the GE foods themselves as well as new allergies to other substances.
NAET treatment and nutritional compensation for methylation cycle gene variants (i.e., NutriGenomics) may reduce some of your chemical sensitivities. I'm not saying this to give false hope - I have significantly reduced my own sulfite sensitivity through supplementation with Vitamin B12 and other nutrients, and I know of others who have had some success with nutritonal supplements and herbs for their own chemical sensitivities.
Here is one link to get you started understanding about
methylation and how it can impact your health (I have no financial connection with this website, clinic, or any of the practitioners):
To get your methylation cycle genetic expressions tested, Dr. Amy Yasko's website offers the same test for half the cost:
Another thing to consider is getting tested for Lyme Disease and related coinfections by a Lyme-knowledgeable physician. Lyme and other chronic infections have been known to trigger the development of and/or increase the severity of allergic and other immune reactivity to a wide variety of things (food, chemicals, inhalants, pollen, etc.). To find a lyme-knowledgeable physician in your area, post a message to the Lyme forum here at HealingWell.
I hope this helps...good luck,
Chronic Lyme Disease, Chronic Bartonella (clinical dx only), Gluten & Sulfite Sensitivity, Many Food/Inhalant/Medication/Chemical Allergies & Intolerances, Asthma, Gut issues (dysmotility, non-specific inflammation), UCTD ("Secondary Lupus-Like Syndrome"), Osteoporosis, chronic Lymphopenia, etc.; G-Tube; Currently trying to wean off TPN.
Meds: Pulmicort, IV Ceftazidime, Heparin (to flush PICC line), Claritin, Domperidone, Colloidal Silver (used topically), probiotics, Milk Thistle, homeopathy.