Why i get my skin swollen up when i get it rubbed against something hard? for example, when i open a big cardboard box,

Dermatographism?: there is an entity called dermatographism where physical contact, usually rubbing, with the skin causes the area to raise and be read, almost like a hive (urticaria). It's cause is not known, and can be brought on by stress or exposure to heat. it is a form of allergy, but often the allergen can not be identified. it is often a chronic condition, but it does not lead to anything serious.