Is mild crps likely to get worse if not treated early? nerve blocks useful?

CRPS: The golden standard is early treatment- this does not have to be nerve blocks - there are different medications can be tried. You must be seen by a Pain doc.

Could centralize: You are best served by confirming the diagnosis, which could be achieved by a bone scan, or even a sympathetic block. This can be managed and treated in a variety of ways, but you will work better with an experience pain management specialist.