Turkey with swollen body



My 8 weeks old turkey has all of a sudden swollen up to twice her size... ok about 8 hours ago.
Top of her head and jowls are swollen as is her entire body. Walks with legs spread becaseu of her size.
She is still eating and drinking normally and her droppings are normal.
I have her in an area where she can get under a lamp which she does in between eating and drinking.

Her two siblings are fine. They have all been free roaming around the garden.

Have plenty of clean water, crumbles and geens.

Can anyone please help? I hand raised these turkeys.