My two white hens started laying around 2 weeks ago like clockwork. One a day about same time each day. My one hen today stayed in the nesting box around an hour and didn't do her usual singing or I should say bragging once laid. I went out and found two white sacks with coils attached to them in the nesting box. Both sacks had fluid in them but i didnt see a yolk. It almost looked like the egg membrane with the whites in it but not yolk or shell. Is this common? What in the world causes this? Is there anything I need to do?