Asking for myself so I can figure out what to ask doctors about after my allergist decided that my situation was beyond his scope and I wait several months for my appointment with the immunologist he referred me to.

From what I've been able to establish by combing through my medical records going back to 1998 and looking at studies, I have to ask about the histamine H3 and H4 receptors - especially H4 - and I want to bring all the background information I can to make diagnosis more likely. I have one severe environmental allergy and have been told by a dermatologist that I was likely allergic to progesterone. Repeated exposure to dust mites seemed to be causing slight sensitivities from skin tests to cause inconsistent (though sometimes severe) systemic reactions including difficult breathing and inflammation of skin on face, suprasternal notch, arms, and legs (listed in order of severity). After several weeks of avoiding environmental triggers, reactions became less severe and less frequent (though I have gotten sick in a new way, which I suspect being related to lower histamine levels cause some other illness that had been in the background to take hold...).

The main question that I haven't been able to find any guesses about that make sense are the delayed reactions to allergy shots that I was getting, increasingly, over several months. The allergist verified that the concentration was very low and had already been reduced. The consistent release by staff at the allergy clinic 30 minutes after injections was regularly followed by worsened systemic reactions in the following hours that took several days to recover from. The most severe reaction is visible in the photos of attached PDF (apologies for the formatting). I have not figured out how to incorporate this into the documentation/context information/questions for the immunologist. Can the delayed and disproportionate reaction be a sign of an issue with the H4 receptor or something related?

Even if no one has a direct answer to this somewhat vague question, I would appreciate any ideas of other avenues to explore.