I would observe BB's poo poo and see whether he cries more. If nothing - okay lah!
I wouldn't bring him to see the dr. at this moment coz' there would be nothing that the dr. can do now. He'd probably just look at BB, feel his tummy and ask you to observe first as well.
But of course, if you're really really worried and you need some reassurance from the dr., you can always pay him a visit.