Pregnant with Mirena?

Hey ladies. I've had the Mirena for a little over a year. This last weekend I had slept with an old friend. Starting Friday night, I was very nauseous and had crazy heart burn...I even threw up. I thought that it was from what I ate and the wine I drank. But last night, I woke up with crazy heartburn and nauseous again. I'm afraid to take a test because it has only been a week. Could I be pregnant? What's the protocol of getting pregnant with an iud?