Most of us on here don't believe in colon cleansing, especially if you have D already (why have more???). A couple of people with C have tried them, and they're better for a couple of days and then they go right back to being constipated. If you want a good purge, there are cheaper ways of doing it... namely by the same method used for colonoscopies--Fleets Phospho Soda or Go-Lyghtly.
Be advised that a complete colon cleansing can sometimes wash away the bacteria in your intestines until you have too little or too little good bacteria and you can end up with diarrhea and be worse off than before. Most doctors do not recommend them either.
The only time I would tell someone to go for it is if they are constipated all the time and they have something coming up--wedding, vacation--and they need to be constipation free for a few days. But, still, the old-fashioned products are usually cheaper and since doctors recommend them, you know they're as safe as you can get with any laxative.
You need to have your "bubble" checked out by a doctor. It could be that it's only an isolated pocket of gas, but the fact that it doesn't hurt makes me suspicious that that's not the answer. If it's always in the same place, that's also a sign that it's probably not gas. It may be a hernia. I had a friend who had them and she had little bumpy-squishy places on her abdomen too where her intestines were poking out where they shouldn't have been--and hers didn't hurt or bother her. And just because I'm paranoid about these things, I would suggest, unless you have an abo****ely wonderful doctor, that you go to a doctor that doesn't know you have IBS and don't tell him that you have it so you can get looked at in an unbiased manner; a lot of people on here have had serious problems overlooked because their doctors just dismissed their symptoms as another manifestation of IBS.