10 month old sleep position

I don’t complain about my LO sleep, only her sleep position.

My LO sleeps and wakes about 2-3 times per night. Whenever she wakes up (drowsy at first), she sits up.

If I put her back to sleep position (tummy), she would push herself sit-up and cries.

At first, I thought she wants to be in the position like when she is in a carrier. But no, she also cries.

The only way works is that when she just sit up, I quickly give her my arm to let her head rest on, she would fall back asleep. 😅

I wonder why she sit-up.

Could she have a reflux? Nightmare? Teething?