it might be also because of worms in the stomach. my daughter used to do it and then when I dewormed her she used to stop. so maybe deworm her and she might stop.

It's very normal for young children to grind their teeth. It's a fun sound for them , it gets them attention and also can be a relief from teething as the gums are still tender.

Hi. My child still does that at times too. Especially while sleeping. Its a phase. Do not worry over it.