Suggest Treatment For Severe Congestion And Headache

Have what seems like a bad cold/flu- severe congestion, headache. Not coughing a lot but when I do it's bad. Had chills last night initially my temp was 96-but I so have low blood pressure and then it was 99. Only thing that helps is combination of Advil and theta flu which had acetaminophen. When I take my temperature now with head scanner, my right side is 98 and my left side is 95. Still feel weak but in general felt better today. Started feeling slightly sick 2 nights ago. But I have been sick so many times this year, before this have had stomach virus 4 times - twice in January, once in June and once in November. This past month I've been taking vitamin c and probiotics. Thought it was helping but I guess not. What do you think could be wrong?