Positive breath test: what should I try first?

I finally got a positive breath test (hydrogen dominant, methane negative) after years of IBS-C-ish symptoms: big post-meal bloating, pressure under my ribs, lots of trapped gas, brain fog, and the feeling that food just sits there. I have not started any treatment yet because I want to be methodical and not throw 10 supplements at it.

If you were in my shoes, what would you try first for the best chance of actually moving the needle?

Options I'm considering:

1. Prescription approach only (antibiotic course) and keep everything else simple

2. Herbal protocol (oregano/berberine type route) because I am nervous about antibiotics

3. Focus on motility support first for a few weeks before antimicrobials

4. Diet first (low fermentation or elemental) to get symptoms under control, then treat

A few important things: I do better when my nervous system is calm, and I get worse if I restrict too hard for too long. I also tend toward constipation even though I am not methane positive, which is confusing.

Looking for recommendations on what sequence makes the most sense, what to avoid combining early on, and what you wish you had done right after your positive test. My main goal is reducing the daily distention so I can function at work and stop planning my whole day around my gut.