My skin stings whenever anything scratches it. the sensation is all over my body and is similar to allergic reaction. what causes it and what can i do?

Histamine possibly: If the scratch produces a red bump and flare you could have heightened histamine response, mediator of allergic reactions. At 45 in the perimenopausal stage, look at your life and increase health: avoid tobacco smoke, alcohol, eat lower histamine foods, take enough vit d3 and vit k2, get a good night sleep, move through the day and learn to manage stress well. See kelly mcgonigal's book.