Doctors mustnât give your boyfriend antibiotics before administering tests to diagnose the cause of any condition. Chlamydia is not found in the urine but in a sample taken from the urethra before urination. If antibiotics are given before the test or he urinated just before the test was done, the results might appear false negative.
It is also possible that you tested positive for a Chlamydia infection a long time before you met your boyfriend. A Chlamydia-infection has the ability to remain dormant without symtpoms or with very minor symptoms in 30-50% of all cases.