Fecal transplants are literally just eating shit except it has been blended with saline to make it more palatable.

Why do doctors complicate things? Simply sucking on a turd occasionally is enough to give your gut biome a booster. Even if the IBS is so bad that you have turbo diarrhea you can use a spoon or freeze it like an icepop. The recycling essentially gives the good bacteria a longer transit time through your system i.e. more time to replenish and dominate over the bad bacteria.