Adrienne Maloof & Paul Nassif -- Dueling Explanations on Son's Injuries

The 6-year-old son of Dr. Paul Nassif and Adrienne Maloof was taken to the ER this morning for injuries to his hand ... but there are conflicting stories as to how the child was hurt ... and now L.A. Child Services is involved.

TMZ has learned ... Adrienne took 6-year-old Christian to Cedars-Sinai Medical Center in L.A. early Monday morning ... and told doctors she was concerned he had several broken fingers.

Sources tell us ... Adrienne told the doctors the injury occurred while Paul was watching the boy ... when they were playfully kicking each other and Paul pushed the kid to the ground, causing the injury.

We know ... Paul spoke with social workers after Adrienne made the allegations ... and told the officials he NEVER kicked his child.

Sources say Paul told the social workers the injury occurred at a school carnival -- when Christian fell off of a funhouse step ... and hurt his hand. Paul told officials the nanny was watching the child at the time, while he was buying tickets.