No, if there was a concussion, it was just one. Multiple bumps can make a single concussion worse in some cases. I wonder if you are concerned after seeing the movie "Concussion." Some have expressed anxiety about developing CTE from concussions and bumps they have suffered.

Padded carpet on the stairs can reduced the impact forces greatly.

Whether you lost consciousness does not matter. Unless one ends up in a coma or has low Glascow coma scores, short periods of LOC do not statistical make much difference