I went for a couple of years without seeing a doctor and ended up with adrenal rests in both testes. Your son may feel he can go it on his own but tell him it is not worth it. Try to find a doctor who cares, being a teenager with CAH is not easy, tests, examinations and not something young people want to bother with. I also tried going without tablets and almost died.  Make sure he takes them. Good luck Sam, I know my mother worried more than I did at that age.