You in the UK? Our system is very different. You can't shop around for a doctor in the same way, as even if you go privately you still have to get your GP to refer you. If you're not going privately then you need the funding to be approved if you go outside of your own area. That's not to say it's impossible though. I would look at the websites of nearest private hospitals and try to suss out who has a big private practice - they'll have a secretary who is readily available for starters and if you enquire about appointments there should be at least weekly clinics. Having done that, then do some work with google and figure out where their NHS base is, then ask your GP about being referred there. If there's a long waiting list that's a good sign. If you can afford a private consultation it might be worth it to speed things up.
The other thing you need to do is enquire about their experience of re-dos, or ask the secretary to ask if the consultant knows of a colleague who specialises in re-dos. If your GP is very "user friendly" they might do some ringing round for you.
Hope that helps ...
New stuff: GERD. Interstitial Cystitis
Lifelong stuff: Food allergies, eczema, asthma