York would probably be closer to you if you're in East Yorkshire - or any city really is likely to have a good vet. It sounds like she definitely needs another opinion. Not sure whereabouts you are in East Yorkshire but it could be good to try and find another one closer to home so she doesn't have to travel too far if she's not well. One that knows about small animals and hamsters as well.
I don't know if this is one you've tried already but they have practices around East Yorkshire, and if you click on "Services" it says they treat "exotics" as well.
Surgeries - Vets
Exotics - Vets