Any ideas on why i'm having allergic reactions to certain foods only on my skin?

Food allergy & skin: The most common relationship between food allergy and the skin are hives (marked by raised red bumps that are red and itchy that occur quickly and resolve quickly) and eczema (pinpoint red dots on a red background often with associated dry skin). The skin and the gastrointestinal tract share immune mediated responses to foods, which is why certain food allergies can manifest on the skin.