What can cause pain going from stomach through to back, when I eat the pain gets worse, I feel sick, sometimes sick, stools light in colour, chills?

You need medical. eval. Light colored (like clay) stool might be seen with liver problems like hepatitis, liver cancer or cirrhosis. Ther could be gallstones, biliary duct obstruction, pancreatitis, pancreatic cancer or mononucleosis. White stools can be seen with malabsorption of fat. ECT. Any fever? Recommend PROMPT medical evaluation. Urgent eval for fever.
Gallbladder? It could be your gallbladder. There is no substitute for a good history and physical exam by your doctor. See your doctor. .