11 month old waking up at night crying?

My DD has slept through the night since she was 7 weeks old. We have never really had a problem with night wakings unless she was sick (and sometimes before she could put her pacifier in by herself). The past 2 weeks or so, she has been waking up anywhere from twice to 7 times a night. She cries, but her eyes are still closed and she is laying down. Most times she still has her paci in her mouth. We have tried letting her CIO but it just gets worse (she will cry for up to an hour) and when we do go in, she is asleep just crying. I just want her to get the sleep she needs - and let's be honest, it isn't so great for us either.