Yes, I agree that your back repair procedure is probably the main cause of your C, but if your colon biopsies showed inflammation, and you're not having either normal BMs, or D, then that inflammation is probably playing a part in causing C, (otherwise the C from your back problem wouldn't be so persistent, because the MC would "loosen it up" a bit).

At least, that's the way I see it, FWIW.
I hear you, because I spent most of my life with C, until one day the D started, and wouldn't stop. After it stopped, it alternated with C, on roughly a 10 to 14 day cycle, until I finally got my diet corrected, and my gut began to heal.
Every cloud has a silver lining. With a regular daily dose of MOM, you will never have to worry about having a magnesium deficiency.
Luve,
Galahad