I am sorry to hear that you have had a sore throat
for the past 5 months, and that it doesn't seem to be getting any better. I know that you have already been to the doctor
twice, and you want to avoid going back to the doctor because it is expensive, but I am going to recommend that you make an appointment to see an otolaryngologist
(ears nose throat doctor). The reason is that there are many different causes of chronic sore throat, some of them can be very serious. The ENT will be able to examine you thoroughly, including doing a flexible laryngoscopy that will rule out some of the more serious causes for sore throat. A flexible laryngoscopy is a scope exam were they will pass a small scope through your nose to examine your nasopharynx, pharynx, and larynx (back of your nose, throat, and voice box). It is true that post-nasal drip can cause a chronic sore throat, but so can reflux, and most importantly sometimes chronic pain is one of the first signs of a head and neck cancer (such as a tonsil cancer, base of tongue cancer, or laryngeal cancer). Hopefully the ENT is able to rule out something bad like a cancer, and then will be able to help treat your sore throat. I wish you the best of luck.