Read the following paragraph and answer the question. Give ONLY the answer, no other words or explanation.

For example:

Answer: <most likely answer, as short as possible>.

Paragraph: It hurt . Terribly . The blonde grimaced as a stream of blood dripped down his arm , splashing onto the floor . Mello gripped his shirt and pulled it over his head , falling back against the wall a moment as the sleeve was peeled off .

Question: What may be the reason why he fell back against the wall ?
Because of the pain .
He may have been weakened or shocked.