What Are The Side Effects Of Femikadin 20?

I recently saw a gynecologist for the first time and she did a regular check up on me. She prescribed a contraceptive pill to me called Femikadin 20 because I have irregular periods and also recently became sexually active. I was told to start this medicine the first day of my next period and that the pill immediately prevented pregnancy on day 1. Later, when my check up results came back, she diagnosed me with chlamydia and prescribed a medicine called Doxyhexal which I had to take for 9 days. I believe she told me that I could take both medications at the same time, but when I picked the Doxyhexal up from the pharmacy, the woman said that doxyhexal interferes with the pill. However, online research suggested that it was very improbably to interfere. The day I had to start taking Femikadin 20 was the last day I took Doxyhexal. I took the Femikadin in the morning at 9:30 and the Doxyhexal in the evening at 21:30, as I always did. The Femikadin package said that I could start the pill on my 2nd-5th day of my cycle and it would then be valid 7 days later. However, I chose to take it on the first day. Will the overlap of these two medication by one day influence the effectiveness of the contraceptive? Also, I am very confused as to how I could have gotten chlamydia. I have had one sexual partner and he is my boyfriend. He also has never had any other sexual partner other than myself. I informed him that I had chlamydia and he took a blood and urine test to see if he had it which, he did not. Just to be safe though, he was treated too. I read that the only way chlamydia can be transferred is through sex, nothing like sharing towels or bathrooms. I had a non-serious boyfriend before but we only had second base contact (i.e. fingering) which shouldn t pass on an infection. I heard that babies can be born with chlamydia if the mothers have it but I doubt I would have had it all my life without it showing up on some sort of evaluation, considering I ve had many blood and urine tests over the years. How could I have gotten chlamydia?