There could be other causes than food allergies. Like Gastroparesis. I recommend seeing an allergist and a GI doctor to try to figure out if the problem is allergies or a GI issue.

I vomit if I eat Vitamins, Corn Dogs, or anything made at McDonalds. I am severely allergic to Corn and several other foods. My sister on the other hand has GI issues and vomits due to non-allergy related problems.

Veey good possibility. I am allergic to eggs and I throw up if I eat

It could be any two or more items that you have eaten. E.g carrots and chicken, cheese on brown bread.
I would suggest a food diary and see what might be culprits. I was amazed with mine after eating chicken in all sorts of ways for over 50 years that chicken had become a major problem. Even a chicken stock cube in something sets me off. Many vegetable soups have chicken stock cube. Best of luck working out your triggers

just vomiting ? no. could be other physical reasons, get a medical view.

My triggers are liver eggplant and broccoli every time I eat them I vomit but does that mean I am allergic to them