Hi J.,
The oatmeal thing may work. I am thinking that it could be the teething at that age. Feel around the inside of her mouth to see if any teeth are cutting through the gum. If so, try swabbing in inside of her mouth with orajel when she wakes up in the middle of the night or give her a little bit of baby motrin. (Of course as perscribed.)
Also, it is easy for friends to say what your baby should be doing. But all babies are different as all moms. I personally found that sleeping through the night happen in waves. My babies would sleep through through the night for a while then hit a new milestone that would interupt the sleeping through the night. Example: growth spurts needing to eat more, teething, night terrors, potty training, growthspurts again - having pain in legs and arms for no reason.
Have fun with your baby girl and ...
Lots-o-Luck!
CJ