I have a similar issue that I just found below my ear, but on my jaw line. I was sick with a sinus infection for a week, and then partook in NYE festivities (bad idea). When I woke up the back of my jaw line leading down to my neck (in the joint of my jaw and neck) was really sore. Yes, it happened, literally, over night. The soreness subsided two days later, but now there is what feels like a large lump. I noticed in the above message that if it is "movable" than there is less to worry about (maybe), and it does feel like its attached to a vein or something (but not just floating around). I set up a doctor's appointment, but there was a hiccup with my health insurance and I was forced to re-schedule for another week. I am extremely nervous about this and cannot concentrate at work or sleep, because I am afraid it is cancerous. Does anyone have any insight onto what this might be and possibly the severity of such a lump?
I also have a swollen lump below my jaw in the right side - it may not be a lymph node - it is possible that it is your submandibular salivary gland. Check with your dentist - they know the anatomy of your mouth and jaw area. Typically the submandibular gland will swell without any pain, whereas swollen lymph nodes typically do exhibit pain of some sort. As a general rule of thumb, if you touch it and move it around and it feels stationary, as if it is stuck to something, I would do much further research into it.