Should I be worried?

So question for my breastfeeding mommas. My son got his vaccinations at his 2 month appointment and he got an oral one. I can’t remember what it’s called but the nurse said it was like a stomach bug. She said if his poop is runny more like liquid I should bring my son back in. So as we know breast fed babies poop usually looks runny ALL the time. My sons poop looks more liquidy and he’s not pooping as frequently. He has like maybe 1-2 mayor poops and more wet(pee) diapers with like a tiny bit of poop. should I be concerned and take him in or is it normal?