Writing a character with amnesia

I'm working on a webcomic in which the main character has amnesia from head trauma. She was an experiment and when escaping she hit her head. She has one sentence of dialogue to the other main character saying that "she's in a hurry" before she passes out, and when she wakes up she realizes that she can't remember anything except she had a feeling that there's something important that she needs to do.

I'm having trouble writing the dialogue for when she realizes she can't remember anything from her life before this moment. I'm not sure what emotions I should channel as she's a very excited and happy character in general.