My LO has always been a fairly good night time sleeper. She's even slept through many of her older brother's crying fits. She wakes up maybe once a night but would usually go right back to sleep after some nursing. This past week, she's been waking up every night crying bloody murder. I'll usually nurse her a bit, but as soon as I bring her back to her room, she starts screaming. The first few nights, I tried to lull her back to sleep but she'll whine and squirm and when she gets herself completely awake, she'll want to play. It'll take up to 2-3 hours to finally get her back to sleep. But for the last 3 or 4 nights, I put her back in her crib screaming and she'll eventually fall back asleep after maybe half hour or so.
She still naps well during the day. She takes 2 naps for a total of 3-3.5 hours. That seems to be the right amount of daytime sleep at her age. She could be teething but I've been thinking she's teething for months now and still no teeth. She just started pulling herself to a stand lately so maybe it's because of her development?
I don't mind that she's waking up, I just feel so bad that she's crying so hard every night.

Has anyone else experienced this?