Hi, A trip to an avian vet is your best option! I
I'm going to ask a lot of questions, please answer the best you can. How old is the bird? How much does he weigh? Do you have a gram scale? Do you know what Bragg Brand apple cider vinegar is? Do you have Children's clear pedeilyte? Do you have any clear Karo syrup? What does your birds poops look like, color, consistency, volume? Is he eating and drinking on his own? Is the bird perching? Is his posture the same as normal, describe if not? What does your bird normally eat? Are his eye bright and clear? Is he breathing normally? Do you have any hand feeding supplies if needed, If not go to your local pet store and Katee Exact hand feeding formula. Do you have any animal antibiotics in your home, if so what are they?
Like the previous posters have said, keep your bird warm, the air around him, (ambient temperature), should be 85-87 degrees if possible. Keeping him warm allows him to use what calories he takes in to fight infection rather than burning them to keep warm. Keep him hydrated, you can put pedialyte mixed 50/50 with water in his lower beak or on the front of his tongue. Hydration is very important when your bird is sick! Watch his poops and tell us how they look.
Monday is to far off should your bird need antibiotics. Call regular vet and tell them what you are up against. Ask if they can see your bird and give you antibiotics. Please check back here to double check dosage information.
If you don't understand something ask questions. Many here have a great deal of experience with birds and are willing to help you.
gary