The main problem I have is actually articulating my feelings. Let's try this anyway.

This story does bring on a feeling of pity for Melissa, due to all the unknowns. How did she get where she was? What was her life like before? Who exactly is Maria, and what happened to her? The last two especially, because even through her fractured consciousness and atrophied muscles Melissa's willing to battle a shitload of unknowns to try and find her.

Mechanically, parts of the writing in the italic section are hard to follow (as in sentence structure, not lack of consistent narrative, 'cause that's kind of the whole point), but the bare-minimum punctuation adds a subtle edge that carries the feeling of delirium nicely.

Very good. You've managed to get inside Melissa's head very well. I also like the effect of using italic versus normal text to show real awareness. Good work.