If it is any consolation, if the pain is nerve related, specifically neuropathy, it is unlikely that you can make it worse by getting out for a walk. Exercise can even help re program the pain by increasing blood flow. Even if it seems to hurt more afterwards you won't be causing any damage and the benefits, physical and mental, of being outside and moving far outweigh any discomfort. As much exercise as you can tolerate and of a type that doesn't over stress your limitations is an important part of healing.

You sound as if you are having anxiety issues as well, which is perfectly understandable. You really need a doctor in your corner to help you through this. Proper pain management can give you a much better quality of life, and activity will do wonders for depression which so often accompanies chronic illness. Please don't be afraid to take a walk or to get a second opinion on that scar. I know nothing about this, but that just doesn't sound right.