I did the Camino last fall and after a few days noticed that I got a tingling in my third and fourth toes after about an hour of walking. A few minutes later I would get an unbearable pain in the balls of my feet. Fortunately, I also figured out that if I stopped and took off my boots and socks for about 10 minutes, I could walk for another hour until the tingling and then pain started up again. So, I walked 500 miles stopping and taking off my boots and socks every hour -- it was what I had to do to get to Santiago! The only day I didn't get the pain was one when my boots were full of cold rain.
In Leon, someone suggested that I try to separate my toes, so I wrapped lambswool around them, and the problem was slightly better. By the way, lambswool is amazing stuff, weighs nothing, and is unavailable in Spain, so bring lots with you.
Once back home, the problem was diagnosed as Morton's Neuroma. I had orthotics, but before I try the Camino again I will look for a sports podiatrist and try to find a better solution.