In what manner do you get sick? Vomiting and/or diarrhea? Cramping and constipation? Cramping and diarrhea? Heartburn? Gas and bloating? If it's one of these symptoms, you very likely have food sensitivities and may even have true food allergies. See a naturopath for proper guidance on an elimination diet. Usually, this is all that is required if it is food sensitivities. Allergy tests do not work for food sensitivities, even though they are like hidden food allergies. Food sensitivities are not considered to be true food allergies, but they will still make you sick. Sometimes food sensitivities can become actual true allergies, but not too likely. I test negative for food sensitivities, yet I definitely have bad reactions to certain foods, some of which I can eat in small limited quantities if I'm careful not to over do it. I usually simply avoid these foods, though, because I feel better if I do.
You can get allergy tests done, too, but most likely you have food sensitivities rather than true allergies. It is important to know the difference. A true allergy would be something like anaphylaxis or breaking out in hives. A food sensitivity can make you feel sick and cause digestive issues to flare up.