Minor Head Trauma: This is the most likely diagnosis given the scenario. The baby fell off the bed, which is a common accident in infants, and hit their head. Most such incidents result in minor injuries that do not have long-term consequences.

Concussion: A concussion is a type of traumatic brain injury caused by a blow to the head or body, a fall, or another injury that jars or shakes the brain inside the skull. Though the baby might not show immediate symptoms, a concussion is a possible outcome.
Scalp Laceration or Hematoma: Given the impact, the baby could have sustained a cut or a collection of blood outside the blood vessels (hematoma) on the scalp.
Skull Fracture: Although less common, a skull fracture is a possible diagnosis, especially if the fall was from a significant height or if the baby's head hit a hard surface.

Intracranial Hemorrhage (ICH): This includes epidural, subdural, or subarachnoid hemorrhages. ICH is a serious condition that requires immediate medical attention. Even if it seems unlikely given the context, missing this diagnosis could be fatal.
Abusive Head Trauma (Shaken Baby Syndrome): It's crucial to consider the possibility of non-accidental injury, especially if the history provided does not match the severity of the injuries or if there are other signs of abuse.
Spinal Cord Injury: Although rare, a spinal cord injury could occur, especially if the baby fell in such a way that their neck or back was twisted or compressed.

Depressed Skull Fracture: A fracture where part of the skull is pushed in towards the brain. This is less common but can occur with significant impact.
Cerebral Edema: Swelling of the brain that can be caused by trauma. It's a serious condition that might not be immediately apparent.
Basilar Skull Fracture: A fracture at the base of the skull, which can be associated with specific complications like cerebrospinal fluid leak.