Whatever went on 7+ years ago almost certainly has nothing to do with your current symptoms. A frequently recurring rash at the penile tip indeed suggests the possbility of a yeast infection, especially if you are uncircumcised; or herpes (unlikely); or something entirely unrelated to either of those. A rash on the scrotum certainly isn't due to any STD.
The obvious need is for you to see a health care provider knowledgeable about STDs. A good place to start would be your local health department STD clinic.
Good luck-- HHH, MD