Whats going on???

Hi so im 27 weeks pregnant and my doctors office called today after my appointment and told me i test postive for chlamydia, as you can imagine i went crazy on my husband and immediately went to a clinic and we both got tested and both of us were negative, how does this happen im so confused???? What should i do, I dont want somethinglike this on mine or my childs medical records if this other clinic clearly shows we are both negative for and and all stds!!