I don't know what happened these two days. One budgerigar at home is yellow, and the other is only a little fried. Is it because of the cold weather?

Pay attention to keep warm, or it will be bad if you catch a cold. It is suggested to put some glucose in food and water, which will enhance its resistance and energy. If you have diarrhea, put some oxytetracycline and feed it with glucose. Keep the cage clean and change the water every day (twice a day when putting glucose or oxytetracycline).

Stir-fry wool and feed it cereal to supplement nutrition. If you are feeding millet, it is recommended not to feed egg millet, because it can promote Pippi to reproduce in estrus, which will have an impact on the health of the mother bird. If you don't breed, it's best to let Pippi breed normally, so that future generations will be healthy. I hope my answer is helpful to you!