The werewolf’s fangs sank into the flesh of [spoiler character]'s shoulder as easily as they would the tenderest steak. Ice and fire flashed through her muscles at the same time, followed by a roaring pain that swallowed all coherent thought.
No, no, no, no! she was screaming inside her head.
The pain wasn’t the worst part, though. She was used to pain.
It was the bite itself.
Werewolf.
Bite.
Werewolf bite. Werewolf bite! WEREWOLF BITE!
I'm unsure if people explained fully why this doesn't work, if someone did then sorry, I ramble. I like rewriting stuff to see how I'd go about it, hopefully that helps you.
That whole first line, ignoring how I have no frame of reference for the tone of your novel or any other information.
'sank into the flesh of the tenderest steak'
Is a line in itself that is too overly descriptive about the wrong things, the perspective it is read from focuses from the person *doing* the biting, so no panic or fear is present there.
People do mention the whole 'searing pain' part but you can actively push that further if you focus on the sensations themselves.
Maybe something like:
The werewolf bit down on their shoulder, the teeth sinking in deeper with every flail, every punch.
Failing to get space, the cold of the teeth, the burning of the wound both competing for attention.
Her arm soaked in blood, unresponsive.
Is the screaming her own.
A bite at the back of her mind.
Werewolf. WEREWOLF!
The grinding of teeth against bone joined by the sudden chill.
As a whole going through this, the key things some people will write when trying to build pressure in a scene is shorter sentences, while I'm personally a descriptive writer, so a bit weaker at the skill, you can generally shorten and obfuscate some parts of it.
In my original draft I first aimed at clearing up the perspective drift, the conflict of 'ice and fire' in the same sentence, the competing sensory details having potential to confuse people especially in a place where people can be English second language.
Theres also issues regarding stalling, explaining that 'she is used to pain' kills the screaming in the previous line, it sets up good information about the character, but at the same time ruins that momentum.
Repetition should mutate a bit, which is why ending with 4 uses of the word 'werewolf' can somewhat ruin things, the rule of three is good and you likely aimed for it, but the lines just before were a 4th instance, even if they are on their own lines.
After that it is figuring out what the character can do/see in that moment, your original version doesn't have a single physical action by the character, they don't punch, they don't back away, they don't physically respond at all, all the panic is internal, they don't struggle.
You don't have to name everything the character is doing, because that can detract from the scene, but unless you are writing the character as absolutely passive, people are going to try and get distance, struggle or fight back, and how they respond, even if you then explicitly state that the pain forces them to freeze, is now building that characters personality under stress.
Anyway I wish you luck, it can take a while to find a way to write what you want, back to my self imposed exile for another day.