help !!!!!

I'm so frustrated my baby doesn't sleep during the night anymore since she turned 3 months she's been waking up at night when she use to not wake up until 7-8 she was doing so good! I'm like so exhausted and need a break. Not to mention during the day she doesn't take long naps if I'm not holding her and for her to fall asleep I have to rock her to sleep I need some advice on what to do. My niece is 3 months as well and doesn't give my sister any problems i seriously don't know what to do at times I need some me time. And my husband works out of town and won't be back until Dec 22. Btw my baby will be 4 months Dec 16