Newborn runny poop, when to worry!?

Trying to not be an over protective FTM.

My boy is 10 weeks old and has been a bit 'off' today, and has done quite a few runny poops today, and crying before passing them.

When should I be concerned!?

He's EBF

I had a slightly icky tum myself yesterday

EDIT: 5 really watery poops about an hour apart each... So quite a bit more than his usual. Might be nothing