Hi , maybe she is not comfortable with the bottle or teats ? Try changing them . Happened to my LO and after switching bottle , everything works wonder ... Which bottle are u currently using ?
it happened to us when we didn't use age-appropriate teat. my boy was OK after we changed the teats.
when she drink milk. do not forget to burp her. Observe her weight gaining also
should be milk strike it's a phase can try changing teats