I have odd allergies. I can go for weeks, even months without a problem. I have walked through dust and mold without a single sniffle. Other times, I wake up unable to breathe without sneezing and gagging uncontrollably. Even something as minor as a change in humidity or temperature can set me off. My doctor said I may have rhinitis (the blood vessels in my sinuses are constricted). There is nothing that can be done about that.
Food allergies- I'm allergic to Brazil nuts of all things. I eat peanut, almonds, cashews, everything else in vast quantities without a problem, but a few Brazil nuts and my throat will close up. I'm weird like that.