Im kinda scared

So, I was dumped by my long distance be last month (August 12, to be exact) and had sex the day after with a friend of mine. We'd had sex before, so it wasn't really random. Anyway, a week later we did it again and now my period is late... I have an IUD and I know my period is irregular, but this I usually don't keep track of my period and now that I am I'm really nervous... I already have an amazing son. I don't want there to be some kind of complications because of the IUD, but at the same time I'm not ready for a other child... Any advice?