Period too soon?

Nikki • 21🧚🏻‍♀️

Hey guys just looking for some clarification! I switched from the ring to an IUD Sept 29 and my first two periods were off but then they were on track up until now. I got my period Jan 4-14 (def waaayyy longer than usual) and I stained my underwear today. It looks like the usual brown before it turns into red when I’m on my period. Has this happened to anyone else? Should I be concerned? I wasn’t supposed to get my period for another week or so. Also I don’t know that it matters but I’ve been having unprotected sex and I’m almost 99.9% positive I’m not pregnant. It’s just weird. Any advice would be great!