Thank you, ByronArthurClark

I have 18,000 words thus far.
Your opener...
We as readers, do not know, Shaaierra. Therefore, to begin your story with her name and an action we do not know the reason for (as it relates to her), creates a disjointed introduction. Who is she? Why would she have this pain. You do not want to give the reason for the pain so early in the piece, so you need to zero in on what is around her and let the reader get to know her.
Okay, it is a new story and of course the reader does NOT know Shaaierra, but most will understand pain and shock.
Shaarierra fell backward onto the freezing snow as the burning pain in her head blinded her. The high mountains were flooded out of her vision by a blinding white light which slowly faded as her new surroundings were revealed. She was on a small island in a mighty blue river.
Utilising as many of your words as possible, I offer the following...
* Blinded by the burning pain in her head, Shaaierra fell backwards into the snow. Her nebulose sight glued to the far mountains, she struggled against the pain. A brilliant white light flooded her vision-fear touched her soul. Eyes shut tight, Shaaierra lay there, waiting for her heart to steady. She knew she had to move or die. She waited...
The curious lack of cold tugged at her mind, inching into the fear. Reluctant lids rose, then popped wide. A vast river surrounded a small island-she was on it. How was this possible? *
I have used a fair bit of licence here and you should not copy what I wrote (why would you!). We/I still do not know Shaaierra, but do know there is magic of some kind, she is curious yet has a will to survive and there is either a "baddie" or some medical reason in the story.
My two cents.

Maxie