Why am i still experiencing fatigue 6 weeks after the flu very weak had heart ct scan and blood work all normal. can't resume normal activity?

Cannot diagnose: This could be multiple different things. Whether you actually had influenza or an illness simulating it is the first of many questions that need answering. You are obviously seeing a doctor. Let them get to the root of this. If you are not satisfied, go see an infectious diseases expert. They are very good at working these things out. Good luck.