To me it seems like too much of a coincidence to be anything but the salty gammon causing the thirst. When she was sick was it the gammon reappearing or water from drinking so much? Being sick can also cause dehydration of course, so that may make her even thirstier for a while.
Can you phone your vet for advice? Hopefully she will just get over it in a short while, but I don't know if too much salt can cause anything worse than excessive thirst, so best to check with your vet I think.
Hope she's OK soon, poor girlie
