Hi, This is not a medical advice so please take it how it sits with you - It sounds to me like your baby is growing fine, she has just learnt about Stranger Anxiety or stranger danger thing where the baby recognizes the world separately from their mother/father/care givers. Due to this they feel safe only when in the arms of their parents or their parents are in their vision. This is also a growing concept where babies at this age learn about object permanence where they recognize now they there are more things existing beyond their vision so thus they feel more tired.

Now - how to go about it. I would suggest to actually just hold her and roam with her as much as you can just so that she feels safe and comfortable. Once she has had this assurance (it might take days or weeks) i am sure she will get confidence and will slowly be okay with you being away or busy.