Often when a new baby is arriving, it can be very normal for siblings to become unsettled. At this young age they are aware something is about to change, but can not make sense of the concept of a new brother or sister. The advice given to you by Tresllian is very aligned with what we would recomend. Reassurance is the key to this approach. If you and your partner are consistent in the routine of settling your little one, she will soon get back to having a better sleep pattern. There are some routines that might also help before bed time, like a warm bath followed by a baby massage and a story. Seek advice from your GP for accepted teething gels, this might help with any pain associated with teething.