Welcome to our Forum. I'll be happy to comment. Let me first assure you that the rash you had on your back and head, which is called folliculitis, is a common problem unrelated to the sexual encounter you describe and is the result of clogged pores. Folliculitis is not an STD.
As for the recurring bit of abnormal tissue you have noted at the opening of your urethra, this iis most unlikely to be a wart. Warts do not come and go in the way you describe. My suspicion is that what you describe may well be normal variation in the mucosal surface that you happened to notice. It does not sound like a typical STD. Because this has caught your attention however, I would recommend that you get this checked out by an experienced clinician, preferably a urologist. In the meantime, I would urge you not to pick or pull at the lesions as this might lead to scarring and lasting damage.
As I said above, I doubt this is anything serious. I hope my comments help. EWH
Thanks very much for your help Doctor. I will go and get this checked.