Sore throat past 3 wks mostly left side. pain comes & goes during day and radiates up to my ear when swallowing. very painful. ?

Sore throat: A sore throat for three weeks requires investigation which would include a throat inspection by a physician(to look for pharyngitis, tonsillitis) or a throat culture to check for strep(which is treated with antibiotics) and blood tests which include a cbc and differential cell count as well as a monotest(to detect infectious mononucleosis). See your physician who will order the appropriate tests