Hey. Question. If you came back clear for STD's, don't you mean you were negative? So, your question about safe sex and being cleared for std's is confusing. Don't you mean they eliminated std's as the reason for the issue? So, you won't give a new partner an std if you are negative for any and I wouldn't worry about that.
The antibiotics have cleared everything up by pain in right testicle? When you finish the 14 days, if that is still going on, I would let your doctor know if it continues. You may need a different or second round of antibiotics. I'd do another round of testing to see if the bacteria is cleared. E Coli also causes it and there are other bacteria as well. Use good hygiene. I'm sure you do but be proactive to make sure from now on. Here is an older post from guys who have had this and several were on antibiotics for a full month before it fully resolved. https://www.medhelp.org/posts/Urology/How-Long-Does-Epididymitis-Take-To-Go-Away/show/1141246