basically ive noticed this for the past few days. however the past few weeks ive had an allergic reaction all over my body from a new washing powder so i have been constantly non stop itching (really badly everywhere) and have recently scratched the skin off numerous parts of my body (arms, legs, stomach, upper buttocks). this is what i originally thought this was but now im really really scared its herpes 
absolutely no other symptoms tho although i know that unfortunately doesnt mean anything
dont look like it to me
either herpes or syphilis is my guess
u should visit a doctors have some swabs and blood tests taken given the fact u have had a recent allergic reaction it could be related it could also be an std or a bacterial skin issue either way u need to go an see someone hope it gets better soon