Ok, since it's now been a month since her course of shots has finished and her symptoms have cleared up, I figured I'd share details of Esme's successful pyo treatment here. I hope this might be of use to someone - I was very relieved to know there was an alternate, less invasive treatment other than womb removal for a 20 month old ham
She was given injections of Alizin, 0.12mls on day 1,2, 8 and 15. (if anyone's curious, the initial consultation cost £33 and each shot after that was £5, so the whole treatment was about £55.)
After the second shot her symptoms (faint blood spots in bedding, and pus) completely vanished. They reappeared briefly on the night before her final shot, however the vet reassured me that Alizin works not by vanishing the infection immediately but by flushing it out bit by bit, so this was normal. She added that if I was still seeing Esme's symptoms 1 week after the final shot, I should bring her back for a final additional shot. This was thankfully never needed - please wish us well that it will never be needed!
I truly believe this treatment saved my girl's life, so if your vet is like my first useless one who just waved us away with antibiotics, please try to find a small animal specialist and ask about Alizin!
If you want to read Esme's full story her thread is here:
Pyometra in Female Hammy