Well, I cannot eat fish or chicken w/o constipation. I do not vomit. An orange its juice would send me into IBS-C purgatory. Bland foods are my ticket too. For your Q, I would use a seed butter that is smooth. Lots of folks like sunflower butter. It is nutritious and sold in grocery stores by the peanut butter. Glad egg whites are working for you. Best to you, too!