You have dermographism,  an allergic reaction triggered by medications, foods, infections, certain physical agents like heat, cold, water, sun, other allergens and systemic illnesses. Much less often it is caused by an autoimmune disease, that affects mast cells.  These cells are the ones that release histamine that triggers formation of hives. So the first thing in treatment  is diagnosis.  The diagnostic work-up includes blood tests, urine, stool to check for parasites, and x-rays of the chest, sinuses and teeth.  A prick or scratch test to test for airborn or food allergens is also in order.

You are suffering from allergic dermatits causing dermatographism.. Medicine available for good improvement......As the treatment varies depending on the severity... Send photos of the affected area, by direct online consultation for accurate diagnosis and treatment.