I don't know if having gone to the ER once upon a time for a "missed shot" means that every single doctor that ever treats you, anywhere, anytime will automatically know about it. Pretty likely if it's the same hospital or some doctor associated with that hospital, but some private practice in another town or state, nah.
You might be a tad little tiny bit on the "too paranoid" side insofar as privacy is concerned.
But how about those Prescription Monitoring Programs that pretty much every fucking state has these days? Those really bother me, though. How about those?
Shit, like 8 years ago, I had been going around Northern Virginia, droppin phony scrips all over the place. Then I went to a shrink and he wrote me some Focalin (d-methylphenidate). The next visit for a refill, he asked me about all the prescriptions I had been getting all over the place. He gave me this whole big "I think you need some substance abuse treatment" bullshit. I got out of there with a quickness! Scary.