Lost on the circular path and a startling change

I was inside a large building and following my brother up a convoluted mess of stairs and pathways to what we hoped was our ultimate goal of getting to the outside of the building up at the top to then take a path further to our destination.  At one point I was behind and took a wrong turn and I was in a few rooms that were a mess of insulation, grease and dirt.  I was trying my best to find the turn I was to make and could not find it.  I took one turn and went down a short walkway and I stopped abruptly as there was a hole and when I peaked at it I could see that it was an open hole and dropped all the way to a linoleum floor below some 70 or so feet.  My stomach did a flip and I quickly backed away.  I yelled for help and finally through trial and error reached a path that I caught up with my brother.  He then lead me around a circular path with a series of turns. 

All of a sudden my brother fell to the floor to my left side and was groaning in agony
and it continued to get worse quickly.  I was completely shocked and stood unmoving. Even more startling my brother then changed from his usual body which was a 6 foot something man with a larger but not fattish build to a much shorter and stocky build man with a decent sized stomach.  The worst part about it was that he was heading at me as
if he was angry and intended on hurting me.  I did the smart thing and squared my body to
him and raised my fists to fend off an attach.