Back Pain as AF symptom?

Ti

This is a dumb question. I have cramps in my pelvis always 4-5 days before AF. If you have back pain as a symptom, where do you have it and what does it feel like? I'm currently having like a dull ache in my lower back, just above my pelvis. Considering the timing, I assume it's just a new pms symptom, but I've never had them before.