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Yes, while it is possible for a hernia to recur in the same place, it would seem to be less likely given that you had a successful repair that has held up for three years.
But, it certainly can be possible, and if you are feeling a new "lump" in that area of your incision, then certainly visiting your doctor for an exam would be helpful. Especially if that lump is associated with worsening pain in that area (which you don't have).
The diarrhea probably points more toward the other medical conditions than a strangulated hernia, but again, if you are feeling worse, having your doctor just examine you is helpful, even if it is for a worsening of the colitis.