What Causes Allergic Reaction To Propolis?

I just found out I m allergic to propolis. I had swollen, red, itchy very dry and scaly eyelids for two months off and on and did not know what was causing it. I had suspected some time of allergy, since I had never had this reaction before. I had an allergy patch test for various chemicals and it came back positive for propolis. I drink propolis tea and also use honey and have done so for many years and have never had a reaction. Just wondering what might have caused me to become allergic after all these years and what I can use to counteract the allergy symptons if it happens again