6 month old nap...

My daughter turns 6 months old next week. I never Co slept with her. She has always slept in her crib at night and during naps with no problem at all. Now all of a sudden for the last 4 days, as soon as I lay her down for a nap she wakes up and will only nap if I’m holding her. At night she will easily stay asleep in her crib. It’s only a nap problem. I’ve never had this problem because and I don’t know why it just came out of nowhere but it’s driving me insane. I turn off all the lights and make it super quiet like I usually do. I don’t know 😩😩😩 she even slept perfectly well while teething, she has her 2 front teeth. So I don’t know.