It's a decent enough first or second draft, but could use a lot of filler and a good mix from a thesaurus.  Your use of the word 'felt' is way too overwhelming as well as a few other words.  Try to limit repeating words too often or it can really stifle the story.

And also be on the lookout for inconsistancies, such as if she is wearing a sock, how is the sweat running down her foot reaching him?

On another note, you could try describing the environment and the people who inhabit it.  I know it's quite limiting when you wake up an insole, but who is this mysterious person waking up, what are his theories about how it happened to him, you said he's feeling pain but what kind of pain and how is it affecting him?  What kind of senses does he have being an insole?  Sense of smell?  Complete sense of touch?  Clearly he still has his eyesight and his ears work, but does he suffocate at all in there?  Does the pressure make his bones creak or is he entirely made of insole? What kind of shoe is it he's become a part of? 

There's so many questions you can expand on and answer within the story.  Just be sure to address them slowly through his experiences and you'll make a much stronger tale for your readers to share on his journey of discovering life as an insole in a girl's shoe.