I have one like this now. Listen very closely to her breathing. Pick her up and listen.in my birds case she has a rattling and its respiratory. So I'm treating with baytril then will go to tylan if no improvement. So check her breathing and report back here. My bird was also fine yesterday. Today she is exactly like you're bird. So let us know if when you pick her up you hear a rattling wheezing type sound. If yes its likely a URI. Upper respitory illness. I previously lost two birds with these symptoms and no wheezing.. if she's not eating or drinking consider tubing her for her fluids and food. Looks like I'm going to have to start tubbing myself. I wish you the best. Please let us know what you find when you do a full exam on her. Breathing check her crop make sure its empting like it should check her vent report anything that you find unusal. Then we can go from there. Best wishes to you.