It's basically a carbonated chemical cocktail. You might be avoiding the sugar, but you're getting a shit ton of toxins instead. [Emphasis mine]

A glass of water is a chemical cocktail and there are no substances in Coke Zero that meet the scientific definition of a toxin.

And people can argue all they want that aspartame isn't toxic. Tell that to my brain. If I accidentally ingest aspartame (or any other artificial sweetener), I get severe hemiplegic headaches, complete with blindness and mimic stroke. Not fun.

I realize that you won't listen to any studies that I post or meta-analyses and they wouldn't diminish your personal experience anyway; However, your own admission that "any other artificial sweetener" is a trigger is a pretty good indicator of a psychosomatic response and not an allergic response. The three most popular artificial sweeteners are aspartame, saccharin, and sucralose and they each have different chemical structures and your chances of being biologically allergic to all of them is astronomically small. It's not like being allergic to Advil and Ibuprofen which are the same thing it's more akin to saying "I am allergic to all things that come in pill form" the chances of which are basically zip.

Let's be very clear: psychosomatic does not mean the symptoms are not real it simply means the trigger is psychological instead of meeting the clinical definition of an allergic reaction. The problem is psychosomatic conditions are "contagious" in that the body can accept the idea at a subconscious level from another person. Ie, someone reads about your experience, remembers a time they had a headache that happened to overlap with drinking a diet coke, and accepts at a subconscious level that they too must be sensitive to artificial sweeteners... The body can then cause the same symptoms in the future even though there is no actual allergy. The symptoms are real the trigger is psychological. As such the constant sharing of misinformation about aspartame and other sweeteners likely leads to the reported conditions actually manifesting in some people. The same thing happened with MSG.

Aspartame is literally one of the most studied food additives in the world the confidence level on it's safety is incredibly high.