What is the back pain and itching?

Could be cholinergic urticaria. Urticaria is commonly known as "rash" There are two kinds of chronic urticaria, acute urticaria and chronic urticaria. The etiology of chronic urticaria is unknown, the course of disease is long and the treatment is difficult. It is a skin disease that seriously affects the quality of life. The cause of the disease may be allergic to heat or cold, or allergic to drugs, food, pollen, alcohol or allergens hidden in food, such as food pigments, preservatives, natural acid salts, etc., which dilate the small blood vessels of skin and mucosa, increase permeability and produce localized edema reaction. Cholinergic urticaria: papular urticaria, self-conscious itching. Sometimes there is only severe itching without rash. I occasionally have systemic reactions related to acetylcholine, such as bleeding, headache, bradycardia and mydriasis.