It certainly is hard not to obsess about this. Not only is it painful, it's also unpredictable. Plus, it's common to worry about what the future will bring.
There are a number of medications, primarily anti-depressants, that are commonly prescribed for PN. They not only address issues of anxiety and depression, but also seem to reduce the pain independently of their psychological effects. It may take some experimenting to find the right one. Your PCP can prescribe these, although seeing a psychiatrist or therapist certainly wouldn't be a bad idea.
Don't try to direct your own treatment too much. Let your PCP be the one to decide who to go to next.
Staying active and socially engaged is also helpful, as are techniques such as meditation. Many are discussed on this forum.
Be as positive as you can be. Worrying and questioning why this happened to you will never be helpful. With the passage of time, you will likely get better at dealing with it.