What elimination diet should I start with? Is there a right choice?

I eat 100% clean, and have so for months. It seems like my GERD (?) dosen't care. Still get a gargling sound in my throat, accompanied by a super bad / weird scent - smells like the food I eat weirdly. Brushing teeth helps for about 10 minutes, then the scent is back. I eat a tums - then brush teeth it goes away.

I'm 100% certain that I need to follow a super strict diet, and I'm 100% willing and able to - I basically can't eat what I want to right now away so I don't care.

Please guide me on what to start with, I was going to do FODMAP - but I'm not sure that's the right choice. I also considered carnivore but I already struggle with constipation so I don't even want to try that right now.