You may just have sensitive skin, if so the wrong type of soap or material of clothing (underwear) can cause you to have a rash which may or may not itch. Maybe even a detergent that is too strong. Also it is common for people get ringworms?
Sitting in one place for longer than normal can cause a rash or even bedsores, especially if you're bedridden. Or it could be a new detergent you're using.
