What Causes Soreness In One Side Of Throat?

I am a 44 year old female. I had a really bad cold/broncities for about 2 or 3 weeks. I finally basically feel better except a little sinus congestion. But my concern is I still have a sore throat just on left side. I looked at with a light and Mostly normal except a puffy yellow spot to the left..kinda behind my tonsil. I was wondering if this could be left overs from my cold. I also have a history of GERD. But I dont ever remember having a sore throat just on one side.