If you have peroneal tendonitis, it's considered an injury, even if you don't know the origin. The injury can be due to chronic use and doesn't have to be caused by a one-time event that you remember. An analogy might be carpal tunnel syndrome from using the computer day in day out but no one event that caused the injury to the wrist. There are 3 categories of injury: acute, chronic, degenerative. Yours isn't acute but it could be chronic or degenerative. The prognosis for the different types is different.

Hopefully, when you find a new PCP, he/she can tell you more. When you look for a PCP, maybe you can find one with an interest in musculo-skeletal. At the clinic where I go, the different family doctors have different interests. Whenever I have a sprain or bone pain or something similar, I go to the guy with the interest in that kind of thing. But he is still a PCP and treats the full gamut of body systems. So maybe you can get your "expertise" under the table in this way without having to see an ortho doc. I hope the brace helps give your ankle a rest.

I hate the whole "need a referral for specialist" thing that insurance companies do. I need to see my sleep doctor but must get a referral from my PCP for that. Why? My PCP has no expertise in sleep and so cannot help me with that, and I have an established relationship with my sleep doctor. It just creates more work for the administrative staff to have to give the referral, do the paperwork, etc. And it takes time and doesn't allow me to see the sleep doctor in a timely way. And they wonder why healthcare costs so much when they add in these unnecessary and cumbersome layers of bureaucracy. End rant!