By the sound of it, you have a protein allergy. That is, you are allergic to a specific, or set of specific, proteins. When the proteins are denatured, you seem to not be allergic. This can happen at high temperature, low pH, or sometimes through oxidation. There’s a substantial amount of research on this if you want to look it up. But, for it to be particularly constructive, first you would need to determine to which protein you are allergic