Earlier you mentioned that you use latex gloves. Have you used latex gloves every time you have experienced the hives?
My mother developed a latex allergy over time back when it was not a well known problem. She would break out in hives and puffy eyes every time she cleaned house. The allergy doctors kept testing her for dust, cleaning products, etc. Couldn't figure out what was causing it.
One day, after cleaning, she broke out with hives and puffy eyes AND this time, her hands and forearms developed solid red swelling that stopped at the proximal edge of her gloves. I happened to come home right then and told her that to me it looked like she was allergic to the gloves.
She went to the doctor and told him that she was allergic to latex gloves... he was amazed, started researching and found that it was really a "thing" but that it was rare. (this is nearly 20 years ago). As she was an active EMT at the time and gloving up was mandatory on calls, our department had to order nitrile gloves because the county would only provide standard latex gloves.
Fast forward a few years. We were on a call, the patient was a DOS. While standing around waiting for the ME to show up, one of the Austin/Travis County EMS paramedics suddenly dropped like a rock and developed difficulty breathing and nearly died. Had to STARFLIGHT her out. To that point, she had never experienced ANY symptoms of any sort. Within 48 hours, the A/TC system had shifted to all nitrile gloves.
Latex allergies can develop over time with gradually increasing symptoms, both in severity and type, or can suddenly manifest as a life threatening event.