confused??

So I have had my IUD for about 2 years and I absolutely LOVE it! I've had a baby already while on the pill, and feel so much more secure with this method. I don't get periods, just spitting typically every 3 months or so and it will last maybe a day. I have constant mood swings, which really sucks but I'm working on it. Anyways, last month was my "period" month, but the last few days I've been feeling really sick and kinda crampy. Very tired, and easily irritated... I don't want to jump to any drastic conclusions, I'm just concerned? Has anyone else gone through something similar?