 [ Symptoms ] fatigue sometimes foggy memory lower back & headache pain occasional chest pain [ Disease ] are you getting treatment for your thyroid your symptoms could have several causes it could be a digestive disorder where your system is inflamed and irritated like irritable bowel syndrome it could be a food allergy those can appear at any time during life it could be a sensitivity such as to lactose or gluten it could also be some kind of stomach bug you picked up from a dirty surface or slightly spoiled food start by keeping a food diary write about what you eat and when your symptoms get worse or better try eating very mild gentle foods like rice and potatoes stay hydrated see if that helps if you do not get better bring the information you collected to your doctor   it will help them make a faster diagnosis