Help me figure out what's wrong please

[Muddlingalongalone]

Nursery told me yesterday that for the past 3 weeks Dd2 (2 at the end of the month) has been massively distressed & unconsolable for over an hour after I drop her off apart from breakfast time.
She's been there a year & apart from the first couple of weeks has been mostly fine.
She did this one night with me screaming mama mama, mummy even though I was with her so I can imagine what it's like.
What can I do to help her (& nursery because they are great). Have thought about dropping DD1 at school first so that she can see that it's not just her I'm saying goodbye too & we are doing regular repetitions of DD1 school, Dd2 nursery, mummy work, nana work, grandad golf.
She will move to next room/other building after her birthday in 3 weeks

Is she having visits to her new room?
It might have unsettled her
Have you changed the time you dropoff?
She might be unsettled if she is seeing other parents coming into the room, expecting to see you
Could she take a cuddly toy in with her, or one of your scarves?

Thank you for the ideas.
She is one of the first ones there in the morning, but always has been. One of the little boys does seem to be coming in later so that might be a factor.
We solved the problem today by giving her milk - my idea, they implemented. But she is becoming an increasing milk monster & she's not a small skinny baby!
She did 1 day in the new room - which she seemed to enjoy, she was with the older children who have already moved up, but apart from that no settling in sessions that I am aware of although they have been over there a couple of times in the morning when there has been staff sickness to maintain ratios until replacement staff arrived. Will ask if she was ok when she was over there in the morning. Thanks.
She takes baby or bunny some mornings but isn't particularly attached to anything.
Fingers crossed it's just a phase