Ahh, orthotics. I know there is a lot of literature out there that suggests we all ought to just throw them out and walk on our feet the way God made them. But if you're not going to opt for that, and if you have a foot problem that is not correctible with the standard inserts -- Spenco, etc etc, then you need custom made orthotics.
I think the the problem is that the average podiatrist is not an athlete or long distance walker. I had had my hard plastic orthotics and they served me very well for 20 years or so of adult life. That's because my hiking or long distance walking was limited to a couple of days at a time. I never had a problem with them till I walked the Camino. In retrospect, what was I thinking? How did I think my feet would enjoy banging onto a hard plastic surface thousands of times a day for a month? When I went back to my podiatrist after that first camino, his solution was for me to stop walking so much. That's a pretty good indication that he didn't "get it."
After shopping around from podiatrist to podiatrist I finally found one who offered the "silicone orthotic" solution. As I said, they have been tremendous. I have also endured rounds and rounds of health insurance appeals to get reimbursed. (they are not cheap, about $600). If that's an issue for people, I can go through it in great length but the short version is that in many "standard" health insurance plans, the coding for "medical equipment" is different than the coding for the standard hard plastic orthotic. The silicone orthotics, at least in my area, are only made by "medical equipment" people (typically those who do prosthetics, etc). Though my insurance paid without batting an eye year after year for my hard plastic orthotics, they initially rejected my silicone orthotics. So you may have an insurance battle ahead of you, but if you do, I will help you! It is well worth it.
I completely agree with falcon that you should wear your camino footwear a lot before setting out, not so much to break in your shoes (most hiking shoes/boots, etc don't need to be broken in like the leather ones did), but to get your feet accustomed to the new positioning. And yes, if you get new orthotics, make sure the boot/shoe you are going to wear them in is big enough for the orthotic, because orthotics are likely to make you size up, even more than the recommended sizing up to allow for daily foot expansion.
Good luck with this, Laliibeans. Laurie