Please help! 3 week old chick with water in abdomen- anything i can do??

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I have a 3 week old bantam chick with noticable water in its abdomen.it is around the top of the leg area. It is soft to the touch and doesn't seem to bother it. This chick had a pasty butt for several days after hatch and I cleaned it constantly. It stays clean so I don't think that is related. Does anyone have any advice or suggestions for treating it?
Thanks