You could spread things like poison ivy or a chemical by getting it on your hands and rubbing eyes, etc.
Did you switch laundry detergent or use a fabric softener? I can only use All Free and Clear, double rinse, and no fabric softener on underwear or towels. I only use no dye, no perfume softener sheets on my husband's shirts and things that have lots of static.
Food allergy can show up like this too. Keep a food log/journal, with everything you eat or drink and all medicines as they can cause it too. Note the days and times you have reactions.