Hi.. Thanks for the query.. As per your complain sore throat along with clogged ears and sinus pain can be due to Viral Infection.. There can also be a secondary bacterial infection along with viral.. The medication given to him that is Doxycycline will definitely help in reducing bacterial infection but inorder to relieve the symptoms he also needs to follow other supportive remedies like taking anti-inflammatory painkiller like Ibuprofen, gargling with warm saline solution, doing saline nasal irrigations, inhaling steam.. Plugged ears can be relieved with decongestant nasal sprays containing Xylometazolne or Oxymetaxoline.. Along with it a script of antihistamines like Levocetrizine, decongestant like Phenylephrine and also mucolytics like Bromohexine can help.. Avoid spicy foods and sip on plenty of warm fluids.. Hope this helps.. Regards.