Hello, Zehntuhl:
Regret Prilosec is not very good after the damage has happened. If You think You have an ulcer, then it would help when taking the antibiotics (coffee grounds instead of red blood). It is probably unnecessary.
Coffee that is not 'espresso' style should be safe, sugars like honey are safe. Walnuts should not have caused any problem, but with damaged gut, anything is possible. Need to allow gut to heal; it takes time.
If RED blood in stool, it is proctitis and ulceration of lower tract and will make AS worse, overall. Best to test the fruit with iodine; this time of year fruits can be dangerous (harvested too early/with too much unconverted starch).
Myrrh is much better than Prilosec at easing digestive issues and "Swedish Bitters" has a lot of this in tincture form, also ginger tea would be better than coffee. Then saffron tea (Mexican safflower can be used) is also very good in this regard.
But certainly do get enough EVOliveOil and if in flare, take the GLA 2g--borage seed oil especially right before retiring. NSD Forum is best to ask more questions. Very glad You have had some results with diet, to date.
HEALTH,
John
