Thank you so much for your replies!
I never thought to have a sample sent off for analysis and to be fair to the vets there are 2 of them working on her which does complicate things and causes problems in continuity. One is my local vet and one is an avian vet who is 2 hours from here. I brought her to the avian vet on Saturday only and her plan was to put her on the stronger antibiotics and then providing she had gained enough weight ( she was very underweight when I got her too) next week she is going to give her an anaesthetic and examine her foot properly including xray, remove her band, do bloodwork, chip and dna sex her.
She did drain the foot for her on Saturday but as this was the first time neither of us thought it would reoccur! But I will definitely be asking for it to be analysed next time. The fluid is clear, there is no pus in the foot. The foot is very hot and VERY painful. She is on metacam for pain relief and anti inflammatory. And no, there are no variations in colour on her foot.
She is eating and drinking very well. She was very underweight when I rescued her and has gained 90g so far

! Her previous diet was a sunflower seed mix. She is now on mixed veg, fruit and grains, and a low sunflower seed mix. And she has baby food twice a day with her medicine in it which she takes from a spoon.
Thanks so much for your help folks, I am at my wits end here with her
Siobhan