Regression or what?

I’m losing my mind my sanity everything because my once great sleeper has took a turn and now won’t nap or sleep at all really unless I’m holding her! She has been a pretty great sleeper from the get go. Started sleeping through the night at about 2 months old but now (at 10 months old) as soon as I lay her down she starts throwing a fit. And I’m not talking just crying I mean like a full on kicking screaming throwing herself around tantrum. I can’t sleep train her because even just a couple mins alone in her crib makes her hysterical and she ends up throwing herself backwards or forwards and hits her head on her crib. Idk where I went wrong.. idk why all of a sudden this is happening she has slept in her own space by herself her whole life so it’s not new to her. I have tried putting my shirts on her mattress and it doesn’t work. I need advice on how to get her back on track. I feel like she’s doing it all backwards. She’s seriously sleeping worse than she did as a newborn. This has been going on for about a month now.