Get an IgE blood test -- they prick your finger, take some blood, send it off, and a week or two later you get a little packet telling you about your sensitivities and allergies. Way less painful than a skin test and more accurate for food allergies.

Sensitivities, as opposed to allergies, can also apparently make you bloated and change your mood; when I have peanuts now that I haven't eaten any in ages, I find my tongue swells and my mouth is sore.