Hello
Sorry to hear about the spur.
If you haven't done so already, I'd recommend seeing a podiatrist - they can provide you with some inserts such as heel lifts to take pressure off the spur and also provide you with some basic exercises
The thing to keep in mind though is that whilst you may have a bone spur, it is not necessarily the spur that is causing the pain, rather what attaches onto the spur, usually a tendon. Often this tendon has become overused which has caused it to pull on the bone cause the pain and the spur. Therefore if you are in a lot of pain, I'm not too sure if going on the Camino right away is the best option. However, if you do decide to go, I personally would recommend using hiking poles purely because crutches are not designed for the terrain you will be travelling on and also it is likely you will end up experiencing secondary areas of pain such is in you wrists/shoulders etc.
Wishing you all the best!