C.K.
I recommend the book Healthy Sleep Habits, Happy Child by Marc Weisbluth, MD worked wonders for us!
Also she may be going through separation anxiety from you or she could be teething! So the book will help you understand how to deal with separation anxiety. As far as it being possible teething buy Hyland's teething tablets in the baby aisle at CVS, Rite Aid, Walgreens, Stop and Shop, Shaw's etc.
They are safer than Tylenol or what not so if it is not a teething issue you don't have to worry about giving them to her, but if it is teething you will know because the tablets work GREAT! and she will calm right down and go to sleep.