In a nutshell, you didn't wash the negatives thoroughly after fixing, right?(posted 9712 days ago)In that case, just wash them again. Thoroughly, this time, 30 minutes in running water will do it. You don't need hypo clearing, but it's OK. Use photo-flo to avoid drying marks.
This is a technique that used to be used by newspapers etc in the pre-digital days. Perhaps it still is. Negatives were developed and fixed, given a quick rinse, and force-dried. After printing, the negatives were then washed properly.
Provided your negatives haven't already deteriorated, they will be OK.