Suggest Remedy For Itching And Blisters In Groin Area

Hi doctor,I had protected casual sex with a lady about 4 weeks ago. I went to the bathroom, took off the condom And washed my penis right after. After about 3 hours, i started having serious itching on my penis and scrotum all Over. I week later a spot was itchy again which turned to a collection of small blisters at the base of my penis that turned to a sore and took about a week to heal. Then right after that, another on the bottom of the penis close to the scrotum, then another close to the head and currently a fourth one at the base close to the location of the first one.please what could this be. I experienced this for the first time about 2 years ago after having sex with a girl friend then unprotected. It was only one sore then. I went to the hospital, I did a blood test and a swab of the sore but it was already healing with almost no oozing. The swab tested positive for staphylococcus aureus which I was given antibiotics for. Over the last 2 years, it has reoccurred maybe about 4 time but never have i experiences this small blisters that turn into sores back to back like this.Please what could this be. Thanks.