The cecum is located just below the ileocecal valve...it makes a little pouch below where the small intestines dumps into the colon. The cecum is a breeding ground for pathogenic organisms...candida, bacteria, parasites, etc. You may have a good collection of critters there that stir up when you use probiotics or ingest certain foods. Another possibility is that the probiotics you use are from a dairy source...if you have problems digesting dairy this could cause more gas, and you should make sure to use a dairy-free probiotic.
You might want to try the P&B cleanse or just take Bentonite for a while and see if the gas improves.
If you have already had 11 colonics and didn't find them very helpful, I would definitely suggest that you try another therapist. With that many colonics, a good therapist should have been able to clear you out all the way to the cecum. I don't know what type of colonic you have been getting....I would recommend a closed-system and preferably the Woods Gravity Method.