First - I prepare for camino and volunteering each year by arranging all my annual or semi-annual medical, optical and dental preventative exams in the few months before my travel. This minimizes the need for insurance cover in Europe, absent emergencies. I also arrange my prescription medications with my doctors so I have more than enough on hand to take on my travels.
Second - To provide for acute medical care and possible evacuation back to my home, I stack insurance covers:
1. The credit card I use to buy my airfare provides some coverage. You must read the fine print in your credit card benefits language.
2. I always purchase trip insurance form the airline I use to travel to and from Spain. This insurance provides some coverage while I am in Spain / Europe between the flying dates.
3. My personal insurance cover in the US (Blue Cross - Blue Shield) provides some overseas coverage. They have an alliance with a global firm to identify and provide services to their insured customers. I can access a web page to locate a hospital or doctor in almost any major city. Santiago is included.
If I stack all these resources on top of each other, I am fairly well provided for.
Third - For medical needs that are lesser, I simply pay out of pocket. In 2013, on my first Camino, I had infected calluses on both heels and paid a total of €75, over two visits, to a podiatrist in Burgos to perform surgery on my feet. I was happy to pay.
Hope this helps.