I agree with the others. She will need to be re-evaluated by her doctor to rule out any hidden issues. Then you can decide which approach to take. He pain could be very much related to the surgery she had on her intestines.
Not much information is provided in order to give you a better answer. The calories burned on the treadmill are not always 100% accurate. And I agree with the others who suggested for you to keep track of your BF%, not just your weight.