So about a week ago my girlfriend informed me she had been told by her doctor that she had Chlamydia, I first came to the conclusion she cheated on me because she got tested behind my back a week after she was at a party (on a night we were fighting non the less). On the same day she got the results I got tested (and took the test for it as well) the test came back negative (I was clean). We have had unprotected sex somewhere in between 100-150 times since we starting seeing each other (4 months). We also had sex like 10 times the week before she got tested and 10 times the week after (so i would had been likely to catch it anyways in that period too if the 30% chance saying is true). I confronted her and she completely denied it. What should i think and do?