false negative for chlamydia?

so my FWB got chlamydia.. and we had unsafe sex probably 3 times.

when she told me, I got symptoms too, like frequent urination and pain during urination. anyway, I went ahead and go test myself expecting a positive result. It came back negative. Of course, I was glad I didn't had it.

Anyway, for a few days, I have a stabbing pain in my groin / left testicle that flares up. Any idea if chalmydia could have been tested false negative ?? and is this pain in my groin related?