He is pretty young, in humans that would mean bones are still soft. But anyway you look at it 7ft is a very long way for a 4 month old panther to fall. Did he fall or did he jump? Quads jump out of peoples hands all time unless they know to be careful. All you can do at this point is monitor him carefully, see if any limbs are not moving correctly, see if he is eating and drinking, watch him climb and make sure he is steady, not like he might fall. Last check that he is pooping as he should.
Let us know how the little guy is.