I recently took a chlamydia test and the results came back positive and I am wondering how I could have got it. I have been with my girlfriend for about 2 and a half years and have not slept with anyone else apart from her during this time. She has slept with another guy about 3 weeks ago. Both him and her took chlamydia tests and came back clear, yet mine has came back positive. How could I have got chlamydia if this is the case?