Don't worry about the questions, I'm here to help all I can. If it is gone, explain it how you did to me. Explain how it felt etc. If you have not had a pap in the last year, then I would schedule one to be done (just to be on the safe side and for your own piece of mind) Yes, infection can cause lower back pain and/or even lower pelvic pain too. If you use the above cream I mentioned and it's better or gone by Saturday, and let your doctor know too, then he will have a great idea as well. But still something I would follow up on with your doctor.
At this point, unless you have proof via test results from a lab, don't assume.. I know it's easy to do, but from the description here, STD is not on the top of the list. If you were to get more, then perhaps, but for now and with you not seeing anything on him, don't blame him yet. But as I was saying, it is easy to put blame on it... especially when you know you have been faithful.
You are welcome Hun, if you need anything else, I'm here. If not, do leave me feedback after clicking the accept too.
Best of luck, you can also keep me posted via the PM on this site too..