I had a lower molar removed five weeks ago. The very next morning i woke up with a slight fever and a sore throat on the side the tooth was removed. The fever subsided in hours but since then I have had weakness in all my extremeties, severe back pain, a burning sensastion in my mouth and oral thrush. I also have a rapid heart rate and burning in my sinuses. I have no idea what this could be and the doctors ive seen are baffled as well.