What Causes Soreness And Itching In The Labia?

I went on holiday on 23rd June and returned on the 30th June. During this holiday I had been in the sea and swimming in indoor and outdoor pools. I also had sexual intercourse on the 24th/25th with contraception, but I have no idea about the other person's past sex life. Later on the 25th my menstruation started. It finished around on the 29th and since returning from my holiday I have had itchiness with my labias which has resulted in soreness. It is greatly affecting my comfort levels and is also causing me to worry greatly. Should I visit my GP or are there treatments I can start to resolve this issue?