Maybe...
Regeneration hurts.
Sure, it's not as if she's actually burning alive, as it probably appears to the poor homeless man who'd been trying to help- she hadn't caught what happened to him before the process kicked in. But her cells are rearranging themselves, re-writing her genetic code, to keep her alive- and that isn't a painless process.
She wonders where she is. She stole a vortex manipulator from the Silence, though she doesn't know if she travelled forwards or backwards... couldn't be too far, though, only a few years or so, cause those manipulators were mostly broken and only to be used in emergencies. The one she stole refuses to work now, though she likes it. She has it hidden somewhere safe.
But wait... Is she getting shorter? No... She must be getting younger. Oh darn... But how does she know that? Now that she think about it, how does she even know she's regenerating? Who told her that?
What's going on? Why does she hurt so badly? Why does she look like she is on fire?
She remembers few things, tries to grasp to them before they can slip away. The letter in her pocket, she found it on the orphanage floor, kept it in case se found the real owner. But wait, the real owner of what? No... She'd lost another piece of her memory. She clung to the last thoughts, the ones she'd raised herself to remember. The Doctor is dangerous, Silence Will Fall, my mum's name is Amy, my dad's name is Rory…
My name is Melody.
It took forever to pry the information on her parents' names alone out of the Silence. Fortunately, Melody had been smart enough to convince them that it would be necessary to her mission if she knew who the Companions were.
She hears someone approach, someone scream. Distracted, she loses one of her thoughts, though she's not sure which one. She repeats them over in her head. The Doctor is dangerous, my mum's name is Amy, my dad's name is Rory, my name is Melody.
Something fell on her. Water? Did they try to douse her regenerative fire? Poor humans, thought they were helping. It doesn't matter. The regeneration energy is still burning.
My mum's name is Amy, my dad's name is Rory, my name is Melody.
"Somebody get help!" She must be getting close to ending the regeneration cycle. She can hear outside voices. Though to be honest, she has to struggle to understand what those words mean.
My mum's name is Amy, my dad's name is Rory.
"Little girl, pay attention!" a man says, looking straight at her face. "Stay awake! You'll be fine, we're getting help."
No! No, no, no! She can't remember her dad's name! What was it? What was it?
She can only remember one thing now. My mum's name is Amy... my mum's name is Amy... MY MUM'S NAME IS AMY.
"Please focus! Can you hear me? What happened? What's your name?"
She struggles to speak, and stay focused on the last remaining memory she may ever have. She opens her mouth, and screams her mum's name. But the name gets jumbled... Her regeneration isn't done. Her mouth isn't done. So it doesn't come out right. Whether it collides with a previous thought or whether it is just a coincidence, she says a name that she happens to hold close. Not Amy, but something similar.
My mum's name is... My mum's name is…
Where am I?
What…
Who am I?
The fire sizzles away. The girl is now a toddler, who can't be more than two or three, in clothes far too big for her, with a man close by she doesn't know. She reaches into her pocket, knowing it has something inside but not sure what. Her hand closes on a piece of paper, which she takes out and gives to the man, though she can't tell why. He takes it hesitantly, as if worried it may also catch fire. He reads through it, as the girl curls up in a ball and cries. Cries for confusion, loss for something she's not sure ever existed, and pure loneliness.
The man has finished the letter, and picks up the sobbing child, putting the paper in his pocket. "Don't worry, dear, we'll find your parents. It says they're coming for you, right here in this letter. Till then, you'll have to stay at an Orphanage. I'm sorry. And I'll have to hope that my friend doesn't bring the whole town running in, thinking to find a girl on fire." He pauses, glancing at the girl in his arms, who's slowly stopping her crying. "You aren't understanding a word I'm saying, are you?"
The girl looks up at him. "Mama?" her lips form the word carefully, as if she's not sure she can say it right.
The man nods. "That's right. We'll find her."
The girl tries to remember if her mum had a name. She said something earlier, didn't she. She repeats it, hoping it's right.
The man nods. "That's right. If they do what they say they will in this letter, they'll come back for their little Annie."