Looks like the common Libre rash some people suffer with due to the adhesive on the Libre. There's a group on Facebook (
https://www.facebook.com/groups/393137240837215) where people discuss ways in which they try to minimize the rash or get rid of it completely although the recommendations don't work for everyone. I used to get the same rash but as it wasn't overly bad just really itchy once the 2 weeks were coming up I never did anything about it.