Thank you for your query.
I would suggest that you should wait for a day or two and not worry for one greenish loose motion
which can occur following a course of antibiotics. In case they persist then you can start a lactobacillus
syrup like Nutrolin B or Vizylac
2.5 ml twice a day. This shall recondition his intestinal flora.
I hope I have answered your query to your satisfaction.