MrCuddly
Glad to hear you're already getting results!
Jaw discomfort means you're probably working too hard. All that's required is gently sucking the oil around your mouth, between your teeth, etc. It's not a competition, and vigorous swishing doesn't help at all.
You can get some tooth discomfort when you go from never before to every day. I don't know whether it's because of the reduction in swelling to the gums, or some film that's being cleaned off your teeth or what, but most of us have experienced it, and it goes away.
And it could be that it's worse with more acidic oils. For example I felt it more with coconut oil than flax seed oil.
But don't sweat the small stuff. You're doing one the best things possible for your future oral health (and even cardiovascular health as well). Keep it up!