Chlamydia-uncertain

My roomate is now 7 weeks pregnant and when the vaginal ultrasound was done they also did a pap smear. She has been having problems with her pregnancy already and has been put on bed rest for over a week. She got a call that from her obgyn saying that her pap came back and they found chlamydia. She was tested for chlamydia last november and was negative and then she started seeing her current boyfriend who is also the father of her child. We know for sure that her boyfriend has been faithfull to the fullest extent and we are waiting on his test results. His last sexual relationship was last summer. I guess my question is could my roomate have had chlamydia last november and it slipped under the radar? Or could her boyfriend have had it since last summer and not known? Also, can chlamydia lay dormant and undetectable by testing and then show up? Last question, I swear, can the chlamydia bacteria be genetic? Okay, I think that is it. Thanks.