Lost 4 pounds in week, nausea, abdominal/back pains, heartburn. Tested neg for h. Pylori? Dr said recent bloodwrk was fine. Afraid I have cancer?

Cancer is last on li. Cancer is so rare that it should be last on your list of possible causes. I would advise you to see your doctor immediately so that you do not get dehydrated. A visit to the er is an option unless you can get to see your md on thursday- this week. You most likely have a stomach flu type of illness. Good luck.