Cockatiels - what went wrong?

Question
My cockatiels had two eggs about a month ago. It seems that both eggs hatched about 10 days ago. Yesterday I found some blood in the cage and I found both of the chicks dead but the blood did not seem to come from the chicks. Also i khave no idea when the chicks die. What went wrong? I did not even see the chicks before they died (I just knew they were there because I could hear them). Do I have
to do something to them (i.e. feed or clean them) after they were born?

Furthermore I found one new egg in the nest today. Is it possible for my cokateil to give birth again so soon?

Answer
It is very possible that the chicks has some deformity or there was something wrong with them that the mother detected but we could not. This also could have been from diet issues. I would highly suggest that you get both parent to the vet as soon as possible just to check things out and to make sure that their health is good.

It is very possible for her to lay an egg again so soon, but no good for her as it will deplete her calcium. Make sure she is getting a lot of Calcium rich foods.