could test be wrong?

I would like to know if a test for chlamydia can come up as positive when it is really negative? I had Mirena placed in 2007 after my second child. I did not have a period after having the mirena placed. I then began having bleeding in March 2009. I figured that it was my period. It continued for 3 weeks so I went to see the doctor. I knew that ectopic pregnancy was possible with the Mirena and mentioned that to my doctor(he was a primary care dr). He did not seem concerned with that. He did a pelvic exam and then sent me to the lab for bloodwork. He did not say what he thought might be wrong with me. He just said that he would let me know if anything came of the tests. I did not know what he was testing for. The person that was taking my blood asked me if the test should be positive. I asked what test and he pregnancy test.
So I went home not knowing what was wrong with me. I had a trip planned to drive to Georgia from Colorado and decided that since the doctor didn't give me any bad news and seemed to think everything was alright that I would continue with my trip. I went to the doctor on a Monday and on Thursday I received a call from the doctor. He said that my pregnany test came back positive and he thought I was having a miscarriage. I brought up the ectopic pregnancy again and he still did not seem concerned. He said that if I had any major bleeding or pain to go see a doctor. Long story short, I made it to Georgia at noon on Friday and was at the emergency room at 1 becasue I began having major pains in my abdomen and almost blacked out. Turns out I did have any an ectopic pregnancy and my left tube ruptured. The er dr and the doctor that did the surgery were in shock that the dr at home didn't give me a urine pregnancy test. So while at the hospital the doctors got in touch with the dr at home and he told them I had a chlamydia. He said that he did a test and it came up positive. So before I left the hospital I had a dose of antibotics. I took it even though I knew there was no way that I had it. When I went to the follow-up appt with the doctor that did surgery on me, I asked him about it and he said that someone had to get it somewhere and wrote a prescription for my husband. My husband and I have been together for 8 years and neither one of us have cheated. There is no possible way. We are always together. We are both home bodies. We spend all our time together and don't go anywhere without the other. This positive test has caused major issues in our marriage because we don't understand how I could have had it. I was tested both times I was pregnant as the drs always do and it was negative. Can this lie dormant? Could a test say positive when it is negative? Could being pregnant cause the test to read positive? Please any help you can give me will be greatly appreciated. We try to pretend that it doesn't bother us but it is always in the back of our minds and of course comes up whenever we get into any kind of argument.

[2terrified]

Yes, it is possible to get a false positive.  But it is also possible to get a false negative.  It does not happen often, but it does.  The tests they use are ultra sensitive. Unfortunately, you both have already taken the medication.  The best thing you could have done was have him get tested. If he would have been negative, then it would have been further reason to believe you had a false positive.