Hi, I Have Been Unwell For The Last 7 Days

Hi, I have been unwell for the last 7 days with what I thought was a summer cold - nasal congestion, chesty cough, fatigue and a bit short of breath. I have taken chesty cough syrup and day and night flu tablets. I was starting to feel a little better but now experiencing throbbing headaches and lethargy, still with the chesty cough and nasal congestion, could it be a sinus infection or should I visit my GP?