Why Does My Baby Girl Kick & Throw Her Head When Trying To Sleep?

my 7month old baby girl has been very uncomfortable at night and during the day for naps..since she was born and its getting worse! She does backbends and kicks and throws her head back when she is trying to sleep.seems like she can t get comfortable!!! Its scary to not know whats going on or how to help!! any ideas on what this could be? Thanks and I look forward to hearing back from you!!! Crysal