Maybe it's teething, but I really recommend reading Richard Ferber's book, "Solve your child's Sleep Problems". I know, Ferber got the reputation as the "cry it out" guy, but the biggest take away for me from the book, was his explanation of sleep patterns. Everyone has the same natural rhythm of sleep, where every 2-3 hours we wake up, shift positions, and then fall back asleep. The problem for parents is when their kids/babies wake up during these 2-3 hour intervals and they aren't used to putting themselves back to sleep.
The key to fixing this is to make sure you put your baby to bed when she's still awake, so she's used to comforting herself, and falling asleep. Then, in the middle of the night, when she wakes up naturally, she'll look around her room, know that she's ok, and just go back to sleep.
The other key is to wait a little bit before you go to comfort her. My pediatrician recommended to wait about 15-20 minutes. If the crying is really urgent (like pain), then go check, of course. But if it's groggy (I'm tired and mad I woke up) crying, then wait and see if she can put herself back to sleep.
My son went through the same thing around 13 months where suddenly he was waking up 2-3 times a night. When we reinforced his bedtime routine, really consistently, and got him used to putting himself back to sleep, the problem went away.
Good luck! I hope you get 8 good hours for yourself soon! :-)