I have been dealing with chronic constipation since childhood- unfortunately, for me it never was resolved with fiber supplements or meds. My symptoms are similar to yours- to the point where I stopped going out to dine with groups of friends because I would have to leave the table due to the amount of gas. I was even in the drug trial for Linzess, which worked while taking but didn’t have any lasting effects when you stopped. My go to solution is Australian black licorice- works within a day to relieve the constipation- but again, only a temporary fix. I have done the whole route with gastrointestinal doctor and they just want to give meds- so I prefer the licorice to that. Best of luck, hope your issue resolves.