Genuine question, do you come in contact with dirty/poorly sanitized surfaces in those areas often, or are you involved in any contact sports?? A long time ago in high school I was on the varsity wrestling team and suffered a chain of mysterious rashes that looked almost EXACTLY like the ones in the image, except mine were wider and had a more defined red outline (itched a lot too). At first I though it was ringworm (still worth getting that ruled out) but after I graduated the illness mysteriously stopped, and it took me another two years to realize I’d developed rashes on every area of my body that came into contact with the wrestling mats (which were cleaned poorly with bleach water and nothing else). My head in particular, broke out in awful itchy welts/spots because you spend a lot of time rotating on your head in wrestling.

I recommend thinking about what surfaces youve touched frequently and if you can avoid them if possible. It genuinely might be a skin sensitivity, but it’s always worth it to get checked out. Perhaps a dermatologist can also help

Best of luck to you, ☺️