Welcome to the Forum. I'll be pleased to comment. From the history that you provide, it would seem that you are not at risk for STI. Condoms protect well against STIs and you have not had unprotected exposures. you have a good explanation for the sore on your penis. STIs are not spread from person to person through transfer of infection during masturbation. I suspect that if you have continued to masturbate and/or use sex toys that these may be slowing the healing process and that if you take some time off from these activities the sore will heal quickly. EWH
By the way the only unprotected act I participate in are handjobs. I even wear a condom when receiving oral. Hand jobs are the only act I participate in where I'm not wearing a condom