Place her in some warm water, I fill a small storage tub with warm (not hot but not cold) water and place some epsom salt in it (regular salt will also do) place her inside and allow her to soak for around 15 minutes in a warm environment. You can also massage the abdomen. Most chickens like baths, but mine tend to freak out at first. Just hold her down and she should slowly start to chill. Hope she passes the egg okay! Poor girl.