PMS Symptoms for 3+ weeks, no period.?

I'm posting this here because the women on this board have helped me in the past. I've been on Mirena for almost 3 years. Throughout my experience with it, I've skipped a couple of periods (1-2 per yr) but usually i get it every 28-30 days. When I miss a period, I've always gotten the next one back on the original schedule. The only issue I have with it is that I get a few cysts per year as well and I get a lot of pain and cramping during ovulation time, but it's worth it for the peace of mind. I know periods can stop during Mirena use, however all of the literature I've read suggests that "if it's going to happen, it'll happen within the first year". I've been cramping for 3 weeks now, got sore on and off during the last week (which actually isn't one of my normal PMS symptoms - even from before Mirena), bloated as if I'm due to start, I'm breaking out on my face and chest, but yet no period. It's been over 2 months since I've had a period, and so much cramping in the last 3 weeks has me concerned in conjunction with the lack of period. I've always been able to feel my strings (albeit they're short), but haven't been able to locate them in the last week I've been checking. I highly doubt pregnancy, since the Mirena is highly effective - but has anyone else experienced changes like these after using the Mirena for so long? Mostly anything I can find is related to issues within the first year.