Are Muscle Pain And Sinus Congestion Common Signs Of Having Flu?

I have had flu symptoms now for three weeks after returning home from a very stressful visit with my family back East. I may have an allergy to my cat, but the muscle aches and sinus congestion I think are more the flu. Just when I think I'm OK, I'll start to get muscles aches and fatigue again. Haven't exercised in weeks and don't know whether this would help move it out. Very frustrating.What should I do? Thank you, Diane