Hello,
My DD1 is 3.7yo and has always been a happy confident little girl. She has been in a nursery since she was 9mo and has always loved it there. This last week, however, she has suddenly started becoming very clingy when I've been dropping her off & 3 times this week I've had to leave her sobbing her little heart out. 
She's fine travelling in in the car and even when we get there & I'm taking her coat off, it's just when I'm about to leave she starts.
Apparently she is fine as soon as she settles down & she enjoys the rest of her day there, often gushing about what she's done all day when I go to pick her up. The carers say that they don't know of anything that could be upsetting her there so it looks as though it is just separation anxiety (especially as she has also started crying when my DH leaves for work in the morning). She's also become a lot more affectionate & clingy at home - needing almost constant kisses & cuddles.
As I said, she has always been quite a confident little girl so I don't really know what could have kicked this off?
Any theories/tips on how best to deal with it? It breaks my heart to have to leave her when she's sobbing 