So a few weeks ago I started getting pain under my jaw, under chin and behind ear on right side. I had a bad tooth and started amoxicillin 500mg 3 times a day for 10 days. I also got a root canal. One week later and now I'm feeling a lot of pressure in my left ear, under jaw and under chin on both sides. I don't think the tooth was the issue. The pain radiates from behind the ear to my neck and collar bone on left side. The right side isn't as bad. The pain under Chin is about 1-2inches to the left from the center of the chin. I noticed I feel it more when I look down.