Confused about methane SIBO diagnosis + treatment plan

This may be long, but I am really looking for some insight from others (especially those who may have be in a similar situation).

I was recently diagnosed with SIBO and told I have methane-dominant SIBO, but looking at my test I am definitely Hydrogen dominant too plus IMO. My integrative doctor didn’t seem very confident with my treatment plan and that alone made me feel like this wasn’t a very individualized approach, ESPECIALLY in my complex case.

Here’s where I’m confused: My symptoms do NOT match what I’ve read about methane SIBO at all. I’ve had loose stools, urgency, and go to the bathroom up to 3–5 times a day for the past year or two. Definitely not constipated. Recently I started eating overnight oats, and it’s the first time in years I’m not running to the bathroom constantly. That seems… opposite of slow motility?

The protocol I was given is: Xifaxan, Neomycin, Nystatin, Digestive enzymes, Candibactin AR + BR, Low FODMAP diet (although my sheet is way more aggressive - no rice or potatoes - than actual Low FODMAP diets), cut out all current supplements I am on.

This feels super aggressive, especially all at once. I’m also really concerned about neomycin because of the black box warnings. I’ve seen a lot of people say it made them really sick too. On top of that, I have PCOS and suspected MCAS, long history of gut issues since childhood (food sensitivities, “candida,” etc.), chronic inflammation + nervous system dysregulation, recently developed random rashes that won’t go away, along with hormone imbalance since starting birth control in 2020.. I was NOT told to stop probiotics or berberine (or any of my supplements for that matter) before my SIBO test (which I’ve now read can affect results??) I’m also worried about doing an aggressive low FODMAP because of histamine issues.

Honestly, it feels like we’re jumping straight into “kill everything” without understanding the root cause. And my doctor already said I’d probably need to do the treatment twice, which doesn’t inspire confidence.

My questions:
Has anyone been diagnosed methane-dominant but had diarrhea/urgency instead of constipation?
Did anyone regret doing antibiotics vs going herbal route first?
Has anyone had false SIBO results from not stopping supplements beforehand?
If you have MCAS, PCOS, or hormone issues, did treating SIBO help or make things worse?

Would you pause and retest before starting something like this?
I’m not against treatment — I just want to make sure I’m not making things worse or missing something bigger without figuring out the true root cause.