You may want to try heel cups and/or arch support straps...even an evlaution for custom orthos/inserts. Are you only running in the NB trail shoes? If so, you need to rotate them out with other pairs (possibly other NB models or even other brands and so on).
Try compression wear or other support gear for recovery, as well as running, since the pain seems to appear following your routes.
Wishing you all the best.