Brown discharge for 9 days after period

Hi! I got an a Mirena IUD inserted in March. My cycle is still adjusting but this is the first time I’ve had the brown discharge last this long after a period. It was just like the other periods I’ve had since insertion. Light flow, minimal cramping, lasted 4 days. I have no pain or cramping. I only have one partner, my boyfriend, so no STDs on my end at least. Should I reach out to my doctor for some testing or should I wait longer to see if this goes away? Thank you so much!