It could be a lymph node. People get those also under arm pits and groin area, too. Basically nodes are fluid trapped that your body wants to get rid of. Not serious but can be a nuisance. You are doing the right thing by getting it checked out to make sure what it is.
I'm a Dental technician for 36 years and have seen oral cancerous growths in the mouth. Dental Tech, not to be confused with Dentist or Doctor which I am not. You need to get it looked at for your own peace of mind.
When I feel my jaw it has a little bump coming from the jawbone. It even moves a tad and it's not bone. It's where the muscle connects to the mandibular joint. If I mess with it, it gets uncomfortable. If you are worried about it why don't you see a GP or a Dentist? Any GP can do imaging if you need it, I think that would be your best choice. A Dentist is also very familiar with the Mandible. I doubt if it's anything more than normal muscle tissue. Stop touching it to see if it's still there, you are just irritating it. It's still going to be there. Just from fingering that spot on my own jaw has it aching a little. There is a bundle of nerves in that area. If you keep messing with it you could cause yourself TMJ problems.
I wouldn't wait that long to get peace of mind. Why do you think an ENT would be best? Do they deal with the jaw?
Stay Calm and may the Peace of Christ be with You,