This is separation anxiety :/
Often coincides with mobility, because that does mean that she is capable of physically moving away from you, KWIM?
She won't have enough confidence yet to leave you out of sight, this is normal though. The best thing is to pick her up before she cries and every time you leave her to play on her own (the cot is a good place, she will also sleep better if she has lots of playtime in her cot) make sure you are back before she gets upset so that she doesn't think she has to be "rescued" out of a dangerous situation, see what I mean?
And if you want to get things done at that age the highchair is great... She can see you, you can talk and sing to her and she will have a good view.
When Scotty was in that phase I went around all charity shops here and got hunners of new toys, it really helped him to get over the SA.
And whenever I left him I would only leave him for seconds and then increase the time so that it was gradual and involved no crying...
Does she sleep alright?
Hugs,
Steffi