Suffered From Flu. Extreme Fatigue, Breathing Trouble, Abdominal, Chest Pain, Swelling In Lower Ribs. Possible Reason?

hello, Over the holiday break, I suffered a two week flu . Since then I have not been my self. I have extreme fatigue , nausea, dizziness , and I have trouble breathing. I have extreme abdominal pain and chest pain which the emergency room doctor feels is costochondis. What worries me is that I have swelling on my lower left ribs that is very painful. I have never had breathing problems in my life but now struggle to feel like I can get a deep breath. I know all about costochondis but I have to tell you that it doesn t hurt all that much. I can take deep breath and it is not painful. The swelling on my lower ribs feels very tender and feel like constant pressure on my lower left side. What worries me is the constant extreme fatigue that I can t shake, the pain and swelling and why I feel I can t breath and get winded talking or just walking up the stairs. I thank you for you d time and kind regards from Canada.