I am sorry to hear that you suffer from CFS, I have had it for years and I have also had the condition you describe which developed toward the end of my Liver Cleaning journey.
I found that eating certain vegetables caused the problem, for some reason the food seemed to lie in my stomach and by the time the next meal was due it felt that I was putting food into a already full stomach. I would even regurgitate some food. I discovered that it was better to eat stewed and cooked vegetables rather than salad and if I wanted to eat raw I would stick to fruit. I also followed a food combining regime. I hasten to say that this was only a temporary solution as the condition appeared to fluctuate, sometimes going away all together. I also found that I had to make sure I chewed the food very well. I would make sure that I ate the main meal as late as possible because the abdominal pains were so draining.
It all disappeared last October. I carried out my maintenance flush and I felt this build up of pressure and then a number of pops. I guess the biliary systems finally cleared itself. Since that date allowing for a settling down period the problem has disappeared.
CFS in my case is linked to spinal pain (my disks swell and rupture, sometimes thought to be cause by gluten in gluten sensitive people) and some specialist think that this disrupts the nerves including those that control our digestion. Consequently the digestive system and biliary system get sluggish and clogged up. Liver Flushing with life changes may help you regain you life. These life changes include rhythmic non-impact exercise such as walking and stretching.