Hi there. PLease don't leave your LO to CIO. Tracy Hogg, The Baby Whisperer, felt strongly that leaving your child to cry with any of the popular ( unfortunately!) CC and CIO "methods" broke the bond of trust between Mother and child. And, it teaches your child absolutely nothing! Have a look here if you like:
Cry it out (CIO): 10 reasons why it is not for usThis is all doubly important if your LO is going through SA.
OK, that all said, there is a growth spurt at 6 months that could be affecting her night sleep. Have you tried feeding her right away and see what happens? It could also be a change in her sleep and A time needs. Could you post what a "typical" day looks like in terms of when she wakes, naps, wakes, naps, wakes again and then bedtime? Hope this helps, keep us posted!