For the past three nights, my 8 month old will not sleep unless she's in my bed or my arms. Prior to this, every night she would start the night in the pack n play, wake up once, maybe twice. I would nurse her and lay her back down and she would go back to sleep on her own. But these past three nights have been awful. As soon as I set her down, she wakes up crying and won't stop. It's such a sad cry too. I've been letting her sleep in bed with me as a result, but I can't sleep this way anymore. I toss and turn too much and neither of us sleeps well. Any ideas as to why she's like this all of the sudden? Any tips? I haven't been this tired since she was born!