I don't have any great advice but Annie went through 
very similiar behavior at home a few months ago but
we noticed it was when hubby and I were in seperate
rooms.  She would only settle when we were together,
she seemed to feel more confident.  We just tried to 
spend time together with her and she got over it, but 
it took 4 or 5 months.  She still has issues when we 
drive seperate cars and she can only go with one of
us though 
 
 
Kasey