Same thing happened to us at aound 6 months.
I tried EVERYTHING, what ever someone suggested i tried it, i tried all the things that i agreed with first and if they didnt work or stopped working i moved onto methods that i wasnt as comfortable with.
You know what, there wasnt any one thing that actually worked with us, it was a matter of baby changing and us learning to know what the problem was.
sometimes it was pain, heat, cold, needing comfort, tummy ache, growing pains, teething, bad dream or all of the above.
After a month i decided that i could make one of two moves.
1) stress each and every time she woke, counting the minutes that i was up, begrudging the time and worrying what was the matter
OR
2) go with the flow, resign myself to the fact that MJ is a baby and she is crying for a reason and she NEEDS me at that time and go and help her get to sleep....
I choose option 2..
At the time it is awful and i was very sleep deprived and would be a bit snappy at times... BUT i kept rationalising that this was a stage that she was going through and she would come out the other side, what i decided to do was focus my attention on being soothing and there for my little girl, after all, its unlikely she is going to do this for years and years and the time, effort and just being there for her IS likely to pay of for years and years.
I know that this hasnt realy been helpful, just go with your gut, get sleep when you can and help your little one through this stage, you will find that the more relaxed you are, the easier it is for her.
I do know what you are going through, i sympathise, but it deos get better... hang in there