My two week old eats like crazy then spits up!?

All of a sudden two days ago my little girl (18 days) is wanting for double what she normally eats. Because I've been having feeding issues she's almost exclusively eating milk in a bottle. She was eating 2ozs every 3 or so hours and now she is eating 3.5ozs - 4ozs in the same amount of time! I try offering her a pacifier first or changing her diaper, making sure she's comfy but she fusses and fusses until I give her more to eat. I burp her after but then an hour later, she spits up! It doesn't seem to bother her much but I'm afraid she's over eating or something. Am I overfeeding her? Should I deny the second bottle? What should I do?