Sorry you are going through this! Once your GI Dr. tells you there is nothing, they can do you must find the best colon/rectal Dr to go to. The episodes will get worse, and you are causing more damage and scar tissue in your sigmoid.
I remember mine telling me that on the way to the ER for the last diverticulitis episode on I had. He was sad for me and I could hear it in his voice.
I have never taken OTC for fiber. But, I found that consuming it contributed to my episodes because of the diverticula pockets were getting packed and causing the problem. My go to when traveling was pepto in the morning with a big glass of water.
Please find colon surgeon.

Sounds like you need to meet with a colorectal doctor or surgeon.

I suffer from often unpredictable diarrhea most likely the result of my low anterior resection in 1986.
I fly generally three, sometimes four, days per week for my work and have found some success in avoiding or minimizing bathroom dependence on the airplane. By not eating solid food for 12-18 hours before flying, I avoid a gastrocolic reflex which starts my bowel moving. If I have loose or watery stools within a few hours of a trip I take one 2 mg loperamide which tends to shut down my lower intestine activity for one to three days. If that does not work, I would use Depends.

Loperamide may be contraindicated for your condition and history, so check first with your GI or general practitioner. However, 2 mg taken with 8 ounces of water is a minimal dose and may be permitted. Sometimes after a loperamide, I will end up constipated after about four days. I have had success with 7.5 ml of Dulcolax liquid (1/2 of the smallest dose) also taken with 8 ounces of water. Generally, this produces a bowel movement without excess diarrhea.

The combination of these OTC medications along with keeping notes of outcome has given me some valuable, but not complete, control over by bowel habits. It took me thirty years to realize this because before flying I was always close to a bathroom that I could use.

I take Metamucil twice daily and have since 1986. While that has some impact on forming a solid stool, it has no impact on diarrhea onset

While you have preventive measures planned that hopefully will avoid a problem, wearing a Depends that you do not need is a non-event. And if you do need it, at least you will be prepared

This really makes traveling a whole lot more complex and stressful having this condition. At least with traveling by car you have control over when and where you can stop whereas flying you are pretty much stuck on a plane for an extended period of time. I appreciate your honesty and advice.

There are two Rx for your problem. I have the same thing. I wear Depends esp wen traveling as i will soil myself. I placed myself on Ozempic, which causes constipation to the 10th degree. im also a little chubby and pre diabetic. 30 more lbs to go.

I can understand the embarrassment of dealing with Depends, and always worried about someone finding out. Having said that, after several very embarrassing accidents in public (it was obvious) I decided to do it, and as one person said, if it happens, it makes life a lot easier.

The final straw was traveling for work and waking up to a dirty hotel bed. That was the worst as I had to involve the staff; believe me, explaining that was far worse than wearing Depends. After that, I wear actual diapers when sleeping in hotels to avoid leakage, Depends the rest of the time. Still hard to accept but it has been the lesser of the things to be embarrassed by.

I have suffered with IBS-D for over forty years. Flying is not a friend to people like me. I always sit on the aisle and my husband sits on an isle seat across from me. Also being in a car and having to go isn't especially fun either. In fact I have an app on my phone called We Can't Wait. I have used it more then I would have liked. It finds you and directs you to all the nearest bathrooms. Try the FodMap diet because if it is IBS there is nothing much you can do except watch your diet. I find taking something like Benefiber is one of the worse things I can take. My husband takes it for constipation. I have also been gluten free and mostly dairy free for over fourteen years and that has helped.

I’ve had my 1st flare of diverticulosis in May, still dealing with bouts of diarrhea. Tried the liquid diet & low fiber. I have constant left lower abdominal pain which is stressing me out! My stool sample just came back negative & scheduled for a colonoscopy end of August. Does the abdominal pain ever go away?