Food sensitivities

K.
I just found out I have food sensitivities to soy, dairy, wheat, and peanuts. I'm 24 and have been eating these foods my whole life! I love peanut butter! I have noticed since I cut them out of my diet I don't get hives as easily and I have more energy. Has anyone else developed food sensitivities later in life? What were your symptoms? How did you know?