Please only answer if you’re a nurse/pediatrician!!

My daughter has had this redness on her all day. We can’t get out because we’re getting slammed with snow and without her pediatrician seeing her they can’t tell me what it is. Any opinions?! Should this be something to be concerned about? Should I maybe try Benadryl to see if it eases it up? My little girl is 2 and a half.

Please no bashing, just asking a question!