However, I have had a different encounter with NutraSweet and all Aspartame-based products. This summer I was diagnosed as not only having asthma/allergies (already knew that) but also chemical sensitivities to phenol & formalin (formaldehyde precursor). In my reading, I found an explanation for the Aspartame reaction I had. Once ingested, there is apparently a reaction with Aspartame in the intestines which produces formaldehyde.
Even a small breath mint with NutraSweet can make my bronchi inflame to the point where I can’t even get enough air to speak. My face turns grey-blue, I get agitated (I usually stay calm during an asthma attack), and I’m exhausted for several days. Once I cut out all NutraSweet, it stopped. Although you have not run into this extreme, you may want to look into chemical sensitivities. It’s possible that you have run into a chemical sensitivity rather than a straight allergic reaction.