What Causes Blisters On Back And Forearms With Swelling Of Glands?

My freind lives in Asia and has a lot of unprotected sex with prostitutes, he has probably had sex with over 2000 women in his life. He has pimples all over his back and forearms... recently he had swollen glands in his throat and diarrohea...now I know living in Asia, you can get all sorts of stomach bugs and worms.. but the skin infrection strikes me as being ominous. Is there anything in this or would it just be the hot weather??