My 12 week old has started flinging his head to the right quite violently during naps and early in the morning - what is going on? He flings it so hard that it bounces around. He has a flat head on right side and I've been putting him to sleep on his left side (until he wakes for his 5am feed and then goes on his back - tolerates side positioner last thing at night as he's just fed and is really sleepy) Is he trying to get his head on the flat spot as it's more comfortable ? I'm worried he's going to hurt himself! Any advice please...