Dd is 24 weeks. Brilliant baby, good sleeper etc. but the last few nights she has been v unsettled at night and lies in her crib or my arms shaking her head vigorously like she's trying to dislodge something. When she gets over tired she dies that thing where she flails around with her arms and legs but this is different. Any ideas? Teething? Self soothing? She seems to want to be asleep but can't.