Hi. Thank for your query. Noted the history, albeit short and specific. Note that you have diverticulosis/diverticulitis. Diverticulosis is a condition in which there are out-pouching of the colon but there is no inflammation. But once they get infected they are called as diverticulitis. Coffee has caffiene and many other chemical which act on different parts of body like on brain, kidneys causing diuresis, bowel movements differently. Hence you would get the different problems at different organ levels and since this is very subjective, every one gets different symptoms. It is going to be your keen observations that will know the problems that you can have including blood in stool, gastritis, motility changes with coffee. Coffee in your case looks to be causing increased motility of the intestines and hence the changes that you have noticed. I would advise you to stop consuming coffee. Try tea, if it too causes same problems stop both of these.