trust me, your platy would have more than likely dropped some last week. dont worry she is perfectly fine, but on the save side check your water stats to give an understanding to what could be another reason for her doing thisShes been there for a week or more but the other fish just gave birth today or yesturday. The swordtail hides behind plant. Whats wrong with her? she is pregnant so im not sure.
even though its a different fish the pic of the platy on your other post will give you an idea as both platy and sword are the of the same family groupI cant get a pic until tommorow.