Hello and hope you are doing well.
The symptoms you are experiencing could be due to an entity called sleep paralysis. When this happens in sleep the person has difficulty moving his hands or feet. This is the symptom of a sleep disorder called Narcolepsy. This sleep disorder is characterized by excessive day time sleepiness, sleep paralysis, cataplexy where the person has episodes of loss of muscle function while awake, hypnogogic hallucinations and automatic behavior. You will need to consult your primary care physician, who may schedule you for a polysomnogram (sleep test) to rule out sleep disorders and initiate appropriate therapy.
Hope this helped and do keep us posted.
My daughter as a toddler had sleep terrors, too .. and believe it or not we traced it back to a preservative in one of her medications .. she'd get the terrors when she took the med with that preservative in it, and the generic which had different makeup was fine. Just a thought, as you try to find an answer for your daughter.
Please stop back and let us know how she's doing.
C~