Parakeet sudden death

Question
I bought my 9 yr old son a parakeet for Easter this year after he fell in love with a class pet we took care of during the week of Spring Break. We've had her about 2 months and she's always seemed healthy. My son is incredibly attached to the bird which he named appropriately Easter. From the moment he gets home until he goes bed, you can find Easter hanging around on my son's shoulder...watches tv with it, reads, plays computer, even vacuums with the bird and the bird is just as attached to him. If I'm holding the bird and it sees him, it'll take off after him. Well 2 nights ago my son came to me right before bedtime and said he thgt she had hurt her leg bc she wouldn't put any weight on it. After examining the bird, I noticed her leg was fine but she had problems keeping her balance and kept falling over...didn't want to move around either. She seemed better in the morning, was up eating, drinking, and walking around. My son came home from school, got the bird out and said he had her on his should like normal for a while when she started making a funny sound and fell off. Said she made the sound a couple more times and then stopped moving. He's really upset but wants another parakeet which is fine but I would like to know what caused the birds death so we don't have the same issue come up again. Any ideas? Thanks!

Answer
I can't tell you what happened because there are too many possibilities.The bird could have eaten something toxic like a house plant or other material. They are also very sensitive to fumes and vapors. Anybody in the house smoke? That could be deadly. Burn anything in a teflon pan? That will be deadly. Did it get a chill? Birds are sensitive to temperature changes Is the cage clean? Think about the environment the bird is in - must be clean and the bird must be prevented from eating anything foreign. But if you have a smoker in the house, parakeets will not have a happy life.