HELP CRAZY RASH

Ann
UPDATE: It is Pityriusis Rosea a minor skin condition. I've always know I had it but I've never had this bad of an outbreak thanks for the help!! 
Does anyone have a guess at what this might be? I have really sensitive skin and I went swimming in a chemically treated pool the other day but it's only on my sides and back? I just got back from the beach and google and myself havw convinced me that I have sea lice 😂😂 HELP