Copper IUD, late period, and brown discharge

Hi everyone! I switched from a mirena to a copper IUD about 2 months ago. I had a normal period last month and I am now 5 days late and yesterday I had some brown discharge/spotting it looks just like implantation bleeding (I know that it is normal for there to be old blood before starting your period. But this seemed different to me). I normally have pretty bad cramps before my period and haven’t had any and still not having any actual bleeding. I will be taking a pregnancy test to be sure. But am just wondering if this is something that happens with the copper IUD or not since I am new to it I don’t really now what is normal or not.

Thanks!