1 year old crying in the night- help?

My daughter will be 1 tomorrow and for the past few weeks has been waking up every hour or so, crying hysterically. I never know if she's scared of the dark, has a pain, or whatever as even if me or her dad pick her up to comfort her that doesn't work and she's still crying. I'm losing the will to live as it's every hour or so every night. I don't like letting her cry it out for too long as she coughs a lot and makes herself sick (deliberately) I don't know what it is as she normally would shut up if she got our attention but she carries on even when we pick her out the cot. Any suggestions people I really don't know what to do. Thanks in advance xxx