If the film is brown then you likely have an issue with fixer left in the film. Not good...
The first thing you should try if you don't want to rewash the neg is to scan the neg with different color channels. That might do the trick. The default channel of most scanners for black and white is green. Try red and blue. If you use Vuescan this is easy. If not, scan it as a color neg and see if one of the channels is clean. Looks like you use a Nikon scanner, so you could even try scanning with the Infrared channel (I think you can do that with Vuescan, but I've never tried it.)
If that doesn't do it, then- I am not a conservation expert, but you should wash it to clear whatever chemicals are left in the film to stop any further deterioration. A soak in distilled water with a few changes would do the trick.
If washing the neg doesn't do anything for the problem (it probably won't) then...
If it were me, and I'm not recommending anything here, I would bleach a neg on that roll that has the same problem to see what I was left with. If I am not mistaken, the brown is a form of sulphide left over from the interaction of the left over fix with the film. If that is the case, the spots will still be there after bleaching. Sepia toning the neg might mitigate the problem. If I bleached the neg and the spots disappeared, then I would redevelop it and that should solve it. If you go down this route be careful. You need to use a rehalogenating bleach.
You might want to consult a conservation book. Lots of old prints had the same problem of inadequate fixing/washing.
Hope that helps you.