I have been reading your latest posting. I wonder if you may be experiencing problems with the sorbitol in plums and excess fructose in the papaya. Also, I believe in other postings you indicated you had some problems with wheat. Wheat is high in a substance called fructans. These substances are made up of chains of interconnected fructose molecules. They are also found in things such as leeks, garlic and onions.
The general condition is called known as the short-chain carbohydrate malabsorption or FODMAPs malabsorption (e.g. fructose, lactose, sorbitol, fructans, etc). While this problem occurs in the normal population it seems to be more prevalent in the IBS population. Our guts are more sensitive. Here is a message with links to an article describing the clinical condition and an article on how to manage the condition with diet. Table 1 in the first article has a check list of foods that contain high amounts of FODMAPs that may cause problems. Figure 1 in the second article gives a list of favorable and unfavorable foods for managing the problem. I use these articles as a guide along with Heather's diet to manage my IBS.
Maybe this information will give you more ideas for managing your IBS.
Good Luck
-------------------- STABLE: ♂, IBS-D 50+ years - Science of IBS