My JuJu, who, I'm sorry to say, passed away last month, used to lay anywhere from 5 to 11 eggs at a time. Every once in awhile there would be one that was oddly shaped(longer than usual) or even one that was so thin it would break when I candled it. I have a male and always hoped he'd figure out what he was supposed to do, but he's gender challenged and loves himself far more than any female bird
so we never had any baby birds. I have no clue what causes it and I sure hope your little feathered buddy is ok.