is hysterically crying at some people she doesn't know when they speak to her?
She is usually charming and has a smile for all but over the last week she has done it to a checkout operator in Tesco and a mum at baby clinic. It is definitely these people causing her to cry as she is soothed, looks at them again and starts sobbing again. She then cranes her neck to look at them and cries harder!
Any ideas?