How long can back pain before periods last?

Kate Smith asked: I had to take Plan B twice in the past 30 days and I was supposed to get my period this weekend around Sunday or Monday. On Sunday, I started to get cramps and lower back pain which I normally get right before my period. I expected to get my period on Monday, but it didn't come. My cramps/back pain continued and are continuing today (Tuesday). I feel like I should get my period any second but it's not coming! How long does this pre-menstrual back pain last before you get your period?mid low back pain right sideRelated

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