I haven't been prescribed antibiotics for "normal" illness like a sore throat for more than a decade, but I have taken them for various dental operations (mostly implants), and I hate the way they mess up my digestion. It goes almost palpably wrong.
I wouldn't be surprised by wider systemic effects either. When it comes to the role of the gut biome in our health, we are still in the discovery phase.
I am not sure how to prove this, but more articles like this around gut bacteria seem to suggest a link.