Just looking for an update on your dog's eye. Have you spoken to a vet yet or is there any change in the appearance of it?
Ghilly
Is the lump/sore bright red? It sounds like a condition called "cherry eye" and it is very common in cocker spaniels. It appears literally overnight and it is actually a prolapse of a gland in the nictitating membrane, or third eyelid. A very simple surgery will return the gland to its original position. The condition isn't painful although it looks painful. This gland is responsible for 30-40% of the tear production of the eye. The cure used to be to simply remove the gland, but it was discovered that many of the dogs that had the gland removed developed a condition called keratoconjunctivitis sicca, or Dry Eye, in the absence of the gland, so now they usually simply put the gland back into place so that tear production is not affected. Do you have a photo of it that you can post?
I would put in a call to the vet and take her in and let them have a look to make sure that this is all that's going on. The only drawback for the surgery at this point would be your dog's age. Twelve is considered advanced years for any dog, but as long as bloodwork is done before the surgery and there are no signs of kidney or liver problems, it's a very quick surgery and should pose no problem. Please keep us posted as to what your vet says.
Ghilly