fighter - i used to relate to how you're feeling. when i was 12, i was told i bruxed at night, so i was given a nightguard. i didnt really have any jaw symptoms per se, but i had frequent bad migraines and headaches. in fact, ive had migraines since i was 7.
i've been told that headaches in a child are the first symptoms of TMJD.
anyway, i remained "symptom free" [at least concerning my jaw] until i was 18, and i began to have clicking, popping, facial pain, daily pain, etc etc.