Confused

I had chlamydia i get my partners previous partner gave it to him & he dident know anyways, i got treated but i dident follow instructions i had sex like 3 days after drinking the abtibiotic and unprotected sex , anyways 2nd time i went to the doctor to get tested again it came out borderline which isent yes or no but the doctor prescribed me anywas , i drank the pills & now 3rd time testing i came out negative ! It makes absolutely no sense to ne BECAUSE ny boyfriend made his appointment now he hasent been tested or treated yet so what i had he has to have & if he has it i woukd have been reinfected instead of testing negative , can someone please help me understand this?