Thanks everyone. Not sure if he will consult with the other vet- I don't think he's going to be that pleased to see me to be honest. He is a brilliant vet and I completely trust him- I've been going there for 20 years, but he is not experienced with exotics. If it wasn't for the stressful bus journey I'd take her back to the other place- and still may have to if my vet is not comfortable treating her. I've written down the treatment used by the other vet, and printed the picture of the injection site for axolotls that I found on this site.
I've been lying awake worrying for hours and suddenly realised that the day before the swelling started she had her first bit of prawn for ages. I know this might sound a bit weird, but I'm wondering if there's any way she could be allergic to prawn??
"Symptoms range from itching and swelling of the mouth and throat (oral allergy syndrome) to life threatening reactions."
She was fine with them when she was younger, but apparently in humans shellfish allergy is far more common in adults. I'm unsure whether the swelling from an allergy could have the pus that was present in Burrito's head though....