I've noticed for the past few weeks that I (and other players both on realms and other servers) randomly get fall damage. I've noticed this mainly happens when building upwards (i build up 10 blocks, got 'hit' randomly which caused me to fall). 

Im 100% sure that this is a bug and not a skeleton or other mob attacking me. I tested a peaceful world and I was randomly hit.

There are some videos on reddit with other bedrock users experiencing the problem.