Why would a strict vegan x 4 years have very thick feces for the last few months? Virtually odorless, but very, very painful. About a month ago, I had tiny pebble-like feces for a week or so. I eat about 30 grams of fiber per day, but lately I kicked it up to over 40 grams and added 10 grams of a chewable fiber supplement and 1/4 cup mix of uncooked steel cut oat/millet/wheat groats. I drink a lot of water, green tea daily, 3-4 soy lattes a month. 49 year old Bl female; haven t had any gi cancer testing - waiting on first fecal occult test kit.