I seem to be allergic to chicken, always have been. When younger I was also allergic to milk/dairy, eggs and fish, ham/pork, plus feathers, pollen, cat and dog hair etc. I outgrew all but the chicken and fish allergies. I don't know why this is.
I was given allergy tests as a toddler which confirmed all allergies apart from the chicken/pork, which weren't tested for, I expect because they're rarer.
i still won't eat chicken now, my reaction is mild (cramping, pain, gut-rot type of symptoms), but I can feel off for 2 days or so after eating it. My fish allergy is different, it's more like hives/swelling typical allergy, and more severe.
My DD also has multiple allergies, but completely incompatible with mine. The only food she's ever tested negative to, on an allergy test, is fish. She's not been tested for chicken but seems able to eat it OK.
My mum still maintains that I'm making the chicken allergy up, in order to be difficult, and it's not possible to be allergic to chicken. I was made to eat it as a child
, despite all the proven other allergies.