Good job on having protected sex. You protected yourself from STIs.
Your testicle pain may be a result of trauma (sex may be a strenuous activity), prostate or testicle infection, rarely, vascular or surgical problem. By no means it is caused by any STI.
Most cases of mild testicle pain are caused by tight underwear and resolve within a few days. If your pain is getting stronger or interferes with your normal routine, see a doctor.
You've asked other questions. Actually a lot of them. You had protected sex which is not a risk for getting an std. I am going to ask you if you have ever considered talking to your doctor about anxiety? At some point, I have to conclude that a lot of what is going on with you could be anxiety induced. When we have health anxiety, we feel every tingle and think it is something bad. Regardless though, if your testicular pain is such that it is worrisome, see your doctor. Perhaps you have a UTI or prostate issue.