Both can be true, antibiotics can cause substantial side effects in some people and most people will be fine. Still sucks if you are not one of those most people.

I have never been given a probiotic while getting an antibiotic.

Seems like a good idea. Is that a common thing? Does the evidence support this?

Story time: I went through a dark and stressful period of my life when I was in my teens. After I mostly got over the issues, I went on a vacation with a friend and his family. At one point in the vacation, I ended getting some kind of food poisoning from shellfish that apparently no one else who at the same meal got. Anyway, I eventually recovered in a few days, but it seemed as though I never fully recovered. I had frequent GI issues for literal years.

I sometimes wonder if the intense stress and whatnot that I had experienced prior some how made me more susceptible to whatever illness I happened to succumb to? No way to truly know, I suppose.

After various specialists and unhelpful treatments for what was later deemed to be "IBS", I was recommended to try something by my GP. He gave me some antibiotic (this was 15 years or so ago) it may have been that one -- Rifaximin -- I know it started with an "R." Anyway, my GP warned me that he came across it in some research, and would be willing to give a try, but I was not to get my hopes up.

I took the antibiotics for 14 days. Towards the end of the regiment, I was starting to have symptoms far worse than normal, but I pushed through. 15 years or so later, I basically have no issues at all. Whatever the drug was it was like a freaking miracle cure.