Mirena Problems **possible TMI***

Hey everybody I have been on the Mirena for almost a year now...and as much as I've been loving it I'm thinking it may be causing some issues. I had pretty random cycles but they always lasted exactly 5 days and were normal with no other issues. However this month I've had on and off dark brown spotting. I'm not sure if it's from the Mirena or what but it's freaking me out. I'm going to the doctor on Friday to see but wanted to know if anybody using the Mirena has had the same issue. 😊😊😊 thanks in advance for any insight