What Causes Swelling Under Jaw,stiffness In Neck And Headache?

Today is the 4th day that I think I am suffering from tonsilitis-----symptoms are swelling under the jaw, pain stiffness in the neck, difficulty swallowing, headache, coughing sometimes, runny nose, feeling fatigue sometimes. I can feel the pain is gradually descending from head down my upper arms. I am girgling with warm salt water, drinking warm water(its soothing my throat) and have taken Dcold Total from the chemist for two days. What appropriate medicine should I take?