I've had flu like symptoms for 2 weeks now. the doctor has given me antibiotics for a sinus infection but i'm still feeling achy, breathless, hot and cold and no energy?

Time for recheck: Most uncomplicated viral illnesses get better within 5-10 days, even if treated with an antibiotic for a bacterial infection. The fact that you're going 14 days without improvement in symptoms is concerning. You should absolutely followup with your doctor- they'll re-examine you and see if this is the normal course for your illnesses, or if there's something else going on.