eeewwww!

Is he not having this at home? Or is he only having bowel movements at your place?

Yuck, You lasted longer then me! I would not allow the child to come back on day 2 with that level of diarhea.

Could be an allergy? Milk maybe, if he's that young did they just switch him from formula to milk? Have you talked to the parents, have they seen a dr.? Doesn't sound normal to me.