I have had IBS since my early twenties and I am now 50. I too have tried everything from prescription to holistic and herbal. I have constipation predominant IBS, bit it alternates. I also suffer from sever bloating and cramps.
I have been fortunate enough to be referred to a specialist and have now had quite a few tests done and do have bowel dysfunction. That aside, I was referred to a dietician and have been following the low FODMAP diet. It has helped me tremendously with the bloating and I plan to continue it. It is the best way of eating for IBS that I have tried (and I have tried many). It is fairly easy to maintain. You eat low FODMAP foods for 6 weeks and the reintroduce certain food categories. You find out quickly what your problem foods are.
Here is a link, but you can find lots of information on the internet. I also attach a link of food lists you should and should not have.