I'm sorry for your loss. Like Anne suggested, you might want to take the bird in for a necropsy to find out the cause of death. This way you will know what it was and/or if it was an illness that could be problematic for your other bird.
I called, and the lady told the doc her symptoms, he said he was not sure what they could do. They said bring her in anyways, if she was bad they would put her down. So I got her carrier, but she seized hard so I let her be. Left her with my husband, used the bathroom, and she passed before I returned.
I do not feel an egg.
Husband is now worried about Lenny, as he has been with us. Lenny and Twin were best buddies. She was more quiet as he laid by her side.