Patchy Little Horse

This is my funny looking shedding horse.  

Farrier was here about a week ago.  After trimming Zoie he wanted to see baby's feet.  I hadn't worked with him for a quite a few days, but he was surprising well behaved.  Farrier wants me to work with him a little more before he "trims" anything.  He wants to come out mostly to get him used to having his feet done.  Said he won't really take anything off, but it will be more of a training session and getting used to the tools.  He is going to make sure to have lots of time in his schedule for him so we can work slowly and not scare him.  I have such a great and patient farrier.

We have made leaps and bounds in our training the past few days.  He has started coming up to me more, has become fairly relaxed with touching his legs and have picked up and set down his fronts a few times.  He is still too touchy in his hip and hinds to pick them up.  I found a really "oh no, don't touch me there" spot around his belly tonight.  One more just behind his ears.  He has been a little to nippy esp. when I scratch his neck and back.  Any ideas on how to stop that quickly and effectively?  I didn't want to smack him and make a game out it, so I pinched his lip hard.  I have also tried vigorously handling his lips until he said "hey that's enough" but he never really got to that point and seemed to enjoy it more than I expected.  I even stuck my finger in his mouth and he didn't do much but taste it.