IUD + STD

So I have the Mirena IUD and I was diagnosed for Chlamydia last month. Both me and my boyfriend was treated taking Azithromycin and waited over a week to have sex again, the doctor said to wait a week and it will be out of both our systems so we did, but when we had sex the next time I spotted the next day which is a sign of Chlamydia. Could the spotting be because of the Chlamydia or the IUD. HELP!!!