Thanks everyone. I took her to the vets and the vet said it was full of pus, she lanced it but she wants to operate on her tomorrow to make sure that it is not a grass seed as she thinks there may be a foreign body as she can feel a nobbly bit just above the swelling. Although there was no obvious entry point of a grass seed or anything else.
I haven't stopped bawling since we got back from the vets as I'm not sure I quite trust them. Whenever I we have been up to them for anything, they always seem to be pushing some kind of surgery onto me (as soon as they find out Beanie is insured). I really don't want to put my dog through the GA unless really necessary. I am probably just being pathetic and I guess it is better to be safe than sorry. Sorry for rambling!
xx