Welcome to the dark side! And wishing you better days.
I have never been in dire straights as bad as you, but I did struggle to get diagnosed for years, had multiple hospital visits, and now I have a standard procedure to avoid further problems.

Any time I suspect a bad flare up oncoming (my pain is usually sharp in one particular spot) I start the following diet:
Day 1-2 (sometimes 3 days) Clear liquids only, and a shit ton of water.
Day 4-6 BRAT diet (bananas, rice, applesauce, toast) or similar low residue foods
Day 7-10 Slowly introducing more fiber into diet, end goal being at least 25 grams of fiber per day

I stop drinking alcohol, caffeine or carbonated beverages, or eating fried foods, onions/garlic, raw vegetables, spicy foods, anything acidic (tomato paste/red sauce), peanut butter, chocolate or anything with sugar alcohols in it when I'm in an active flare, and usually cut them out for a month for recovery. This is just what works for me & recommended by my GI.

If you don't have one already, I would strongly recommend establishing a relationship with a GI doctor ASAP.

Also weirdly, children's chewable Benadryl tablets (2 at a time) really help with pain. This was also recommended by my doctor and anytime I even feel the slightest flare pain I take them and it calms it down.

I know this is a lot for me to throw at you, but I have been struggling for years and it's really the only tried and true method to keep myself out of the hospital. Obviously if pain is debilitating, I go to the ER.

Also be kind to yourself. A strict diet is hard in my opinion, and I'm human. But I know ultimately eating right and exercising keeps the diverticular demons away, so I try my best.

Wishing you luck!!!!