..
Without knowing the status of some other factors affecting your
duodenum such as magnesium, calcium and sulfur, the only "safe"
remedy under those circumstances would appear to be Bromelain,
because it won't change your acid situation (which is unknown),
but it has an anti-inflammatory effect and supports digestion, which
are both helpful under those circumstances.

Occasionally taking a probiotic (acidophilus) supplement may be
another consideration.  I would also get tested for the H. Pylori bug
(by blood test, or urea breath test), to rule out its involvement, and
you may also want to either see a professional to assess you for
food allergies, or you could try a rotational diet yourself, to isolate
any offending foods (particularly for diverticulitis).

Reducing abdominal gas is important for diverticulitis, so if insoluble
fiber causes more gas for you, make sure you stick to soluble fiber,
such as psyllium husks.  A pancreatic enzyme complex also helps
with abdominal bloating and certain allergies.