I got on-the-job training to be a pharmacy tech at a Walgreens while I was in college. My state required that you be licensed at the national and state level, but it was just a test and some continuing education credits.
My current state doesn't require either, so the techs are definitely skewed younger. Thankfully I finished college and work elsewhere now so I can only guess at their ages but teenagers seems accurate.
One thing I discovered when I was struggling with mystery stomach ailments was that testing for SIBO/IMO is rarely done even though the treatment can be as simple as a course of oral antibiotics. This is because the test involves drinking a vile sugar concoction and then breathing into a bag every 20 minutes for 4 hours. My gastro didn't do it, I had to ask for the test myself and then travel to a different city to get it done. You've said you've had a ton of tests (I did too) but bizarrely a SIBO test just isn't one of the common ones. I ended up having IMO.