I have sinus infection , went to ER now feel no energy, tired and weak?

Im a 41-year-old female. Ive been sick since December 4. I went to my physician December 6 due to a sinus infection which he prescribed me a zpak. Took enough pak kept feeling worse and very weak. When to the ER and P.A. there said I had an upper respiratory infection was told to get rest afrin and an otc decongestant which I did. Kept blowing lots and lots of green mucus from nasal passage and coughing the same green mucus from my mouth non stop tasting nothing but infection when I swallow. Still feeling horrible and extreme fatigue and weakness. I retun by to the ER 4days ago this time I was told after chest x-ray and lab work that I have a bad sinus infection and bronchitis. The doctor gave me a bag of iv fluids and a bag of levaquin and a prescription of levaquin 750mg 1 a day for 10 days. I have been taking them for 4days the green mucus is still coming up not as much but I still have no energy at all so weak and extremely tired. I still feel no what like me before all of this what is the cause of the unbearable weakness?