do you know of a good doctor in Oregon who helps veterans write NEXUS letters?
No, darn it...I don't know of anyone in Oregon who writes nexus letters. In fact, we don't talk of nexus letters these days, rather we talk about the independent medical opinion or IMO. You don't want the doctor closest to you, you want the doctor who will do the task you need done as professionally as it can be done.
I refer to a small handful of professionals across America who will be able to help you. Have a look here and talk to any one of these doctors or talk with each one https://www.vawatchdog.org/imo-ime-medical-opinions-exams.html