I am sorry your kitty is having so much trouble. I am very concerned about her because she is so painful and uncomfortable, and I feel strongly that no pet should suffer from pain. It is possible that your kitty experienced a fracture or a break, and since she is so painful I think you should take her to the emergency hospital tonight so that she can be examined and her food can be x-rayed. She will also be able to get some safe pain medicines to keep her comfortable. Please do not hesitate to have her seen, fractures are very uncomfortable and uncontrolled pain can lead to increased blood pressure, elevated heart rate and other metabolic abnormalities that make the body work very hard.
Given the advanced age of your kitty (cats are considered to be geriatric at the age of 8), it is possible that she has no fracture but is experiencing seizures or mini strokes that you are mistaking for a broken foot. It is IMPERATIVE that she be seen right away to figure out what is going on. Please keep me posted, and let me know if I can be of further assistance. If this has been helpful, please hit the green accept button. Good luck!