Toddler screaming in pain at night

My little girl is 3.5 years old (😭) and has been a great sleeper all of her life. A few months ago, she started waking up in the middle of the night, SCREAMING & crying in pain, saying “mama!!!!! My legs hurt!!!!!!”. It happened a few times, with no specific pattern. She went a few weeks, and tonight, did it again. She was sleeping soundly, and all of the sudden started thrashing around in her bed & screaming this time that her knees hurt. I got her out of bed, fully woke her up (she was still half out of it), have her Motrin, and settled her down. She’s back asleep now, but I’m really worried. I KNOW the comments are coming about calling her doctor, and I fully plan to do so. I was just hoping that some other mamas on here have some advice or similar situations. ❤️