Many kids stutter while learning to speak. "to be honest the stuttering has tremendously improved, to the point where it rarely happens." The doctor told you to wait and see because it may just go away. You waited and saw it, and it went away. What is the issue? Obviously, you have more information than I do, but there is a huge difference between stuttering and having a stutter. Sounds to me like your son is just bumping against words while learning the new skill of talking. as for the growling, humming, throat-clearing: no idea. Could be a tick, could be he just likes the feeling/sound, could be his throat is sore and this soothes it, could be a million other things.