Hi.. Thanks for the query.. As per your complain it seems that persistent cold and throat pain along with sinus infection seems to be due to sinus infection only leading to post nasal drip and cold is due to sinus congestion and as the sinuses drain through nose the congestion in sinuses causes impression of cold.. I would suggest you to consult an Otolaryngologist and get evaluated and a thorough clinical evaluation and investigations like PNS view x ray or MRI scan can help in diagnosis and treatment can be done accordingly.. You can be advised a course of antibiotics, anti-inflammatory painkiller like Ibuprofen, decongestants like Pseudoephadrine, do saline nasal irrigation, steam inhalation and use a humidifier in your room.. You can also be advised decongestant nasal sprays containing Xylometazoline or Oxymetazoline.. Avoid spicy and chilled foods.. Do warm compresses around nostrils.. Hope this helps.. Regards.