Dead Cockatiel

Question
I've had my cockatiel, 10 month old Francois for one week.  She adjusted well and was so much fun.  She seemed happy and would scramble all over her cage.  I had her on a mixed seed adn pellet diet, with fresh veggies, some friuts and nuts and she seemed happy.  I took her to the vet for a check up, after 5 days and she got a clean bill of health.  Everyone in the office loved her. They recommended a pellet diet called Harrisons high potency bird food. and she took to it right away.  My family adored her.  I loved playing and sitting with her. My husband, reluctant as he was, became quite smitten with her as well.  Yesterday, she began to produce watery stools.  The night before she had been quite sleepy so I put her to bed early.  She spent the next day, yesterday, happy to eat and play, but still, was very sleppy and puffed up and was sleeping in corners, and on the grate of her cage. I called the vet's offcie and they said I should make an appointment, and I did.  I put her to bed early last night and laid a small towel in a corner of her cage.  She crawled onto it and went to sleep.  I sat up watching her until very late.  When my husband came down this morning, she was dead.  I'm heartsick.  I don't know what happened and I just loved her so much.  I feel so guilty.  Why do you think this happened.

Answer
Hello Gail and thank you for your post.
I am so sorry for your loss.  It is always heartbreaking to hear that one of our little feathered friends has passed.
There are many things that could've caused the untimely death of your bird.
The fact that she produced watery stools and became puffed up after the change in her diet does lead me to thinking that it was the sudden change in her diet.
The one ingredient in the Harrisons Bird Food that I can see that is really not good for a bird is the sunflower seeds. (Yes, I did go to the site and find the ingredients)
Sunflower seeds are not good for any bird.  They are loaded with fat, which is hard on a bird's liver and kidneys, and there is no nutritional value to them.  The only reason that they are included in bird food is because they are cheap.
Also, what kind of fruits and vegetables were you giving to the bird?  There are some things that are very toxic to a bird, such as avocados, apple seeds, etc.
On another note, if you were taking your bird out to the office, it is possible that she caught a draft, or there might have been something in the office that made her sick.
If anyone used perfumes, air fresheners, smoked, and so on around her, this may have overloaded her body with toxins that her body couldn't fight off.
There could have been so many factors and without a necropsy, it's impossible to pinpoint what happened for sure.
Again, I am so sorry for your loss.  It sounds like your little friend had a great and loving home.

Please let me know if I can do anything else for you.

Good luck and God Bless.
Dianna