How!?!?! TF!

I started dating this guy in early June. We had sex mid June. I found out one of us had chlamydia we got treated by end of July. I got retested and cleared. But now one of his testicles is swollen! He never got retested. But I never came back positive anymore. Could it be that he had it longer than me because of that swelling developing?!?!?

We fucked up by not getting tested before. Sucks we don’t know who had it. Idiots I know!