Anxious, sick, and lonely
This might be a long post so bear with me, I'll put a tl;dr at the end too for those of you with less time on your hands.
So about a week ago my sister and I adopted our first budgie from a girl who couldn't keep it any more, she said she had two budgies and one of them died, which forced her to find another home for her other one. We were so excited to give this little bird a new, loving home, and brought her in straight away. At first the budgie, Luna, seemed stressed, as one would expect, having just lost her partner and now moved to a strange place, but I kept her covered and spoke to her softly for a few days in the hopes that she would settle in... Fast forward to the Tuesday after (we brought her home on the Friday), I decided to look up signs of illness in budgies so I could be more aware of anything should it come up, and recognized the dreaded tail bobbing in our new friend.
We took her to the vet immediately and were told she was extremely sick and has probably been for a long time. Apparently the conditions she had been living in with her previous owner were comparable to us sleeping on the floor every night, and this was apparently her life for the past two years. Naturally, I was furious and horrified, and we've been trying to make things easier for her since. She's on antibiotics that I give her every night, but she has been trying to bring it back up afterwards, and sneezes or coughs for a few minutes after I give it. On top of that, the past day or so she constantly chirps when I'm around, but it sounds distraught and scared, so I have her half covered and kept warm in another room. I have music and other budgie noises playing for her on and off, which she happily responds to, but I don't want her to get stressed when she can't find the mysterious flock.
The vet said that if she was going to recover from her illness, we would know within 72 hours of her first treatment, but while some things have improved, others seem to be getting worse. Her posture has straightened, and she is less fluffed now, but her cere went pale (it was dark brown which I've been told is related to breeding moods?), the feathers under her mouth are slightly discoloured, and she seems constantly distressed. I'm trying everything to make her new home comfortable but I can't afford another vet bill. She still has the rest of the week left on her course of antibiotics, so I'm hoping things will brighten up after that, but otherwise I'm totally at a loss. She's a beautiful little girl and it breaks my heart to be so useless in helping her and giving her the luxurious life she deserves.
I'm posting here because I absolutely just don't know what to do. She has been chattering today but then sounds sad afterwards, and I can't tell if she's happy or not. Do any of you have experience with anxious budgies, confusing sounds, or birds trying to regurgitate their medicine? If so I'd love some help with making her more comfortable.
Tl;dr: adopted a dying budgie unknowingly, now trying to make life better for her but I have no idea how to.
Any help would be appreciated.