Hello and hope you are doing well.
It could be a hematoma, which is collection of blood in the layers of the scalp. The trauma could have caused this. The hematoma will resolve with time. However, its best to have yourself checked out as suggested above to rule out a fracture. An X ray can help confirm this.
Hope this helped and do keep us posted.
I would think the soft spot was from a bruise. If there was damage inside your head, your brain would swell and you would have real trouble. If your skull were fractured, surely you would have a lot of pain. Still, you could get checked out for it if you are concerned,. Now and then, somebody will walk around for a while with undetected fractures, but I think the pain sets in within a few hours.