A regular vet can give the bird fluids and a antibiotic injection if it is an infection. Please think what the bird has been around today, anything toxic, any fumes, eaten anything different. Has it chewed on anything? What does the last poop look like?
I called two vets crying. One of them took birds. So we drove there. They took her in and xrayed her. They said she might have fluid around her stomach. Her breathing sounded fine but off. So they showed us the xray and there was something on her liver. They said it might be an egg coming up and contricting her breathing, or it might be a tumor. So I told them to take blood and they did. No tumor. Told me to wait 48 hours to see if the egg comes down. Or 36 to see if it comes out. If not they're going to give her an ultra sound and stuff.