Sick for two weeks, started feeling better now sick again. chest congestion, cough, 101.9 fever, achy, fatigue, increased hr. what is it. cold? flu?

Two illnesses ..: in all likelihood. If you started feeling better, that is a good sign that you were on the mend. But then, very unfortunately, you were exposed to a second bug, probably a virus. This second set of symptoms does suggest influenza/flu. See your doctor now. You may be a candidate for Tamiflu/flu drug. You also need to be evaluated for secondary bacterial infection that may have developed.Good wishes

Viral Infection : your symptoms are consistent with a viral infection in this case perhaps influenza. Because their are medications to shorten its course if you start them early you should be seen and evaluated ASAP.