I am sorry but you asked the question
1. The horse might have some arthritis in his leg(s) and it hurts when the nails get pounded in.
2. There are holes in the training and not the horse's.
I am sorry but, and I quote:
I have had my horse for 9 months now and today he was shod for the 5th time. This was also his worst time yet.
You are doing something wrong and my suggestion is to get an experienced horse person to help you. It doesn't have to be a professional trainer. Someone with a lot of years handling horses, maybe even one of the farriers?
At any rate, you are letting the horse get away with too much. It has been giving you subtle warning signs all along but those signs have been ignored so he is taking more and more liberties.
This comes under the category of new (or newer) horse owners who say "this is not the same horse I bought xxx months ago"
If it took nine months and five shoeings for the horse to get to this point, it must be long-suffering and have the temperance of Job.
Please get some help from a person who can physically be there, before what sounds to be a great horse gets ruined
Also, it doesn't matter how old your daughter is, it was not safe to
I had my daughter stand in front and when he jerked, I held, after he stopped jerking,
You are very lucky the horse didn't decide to jerk forward and step on her. Horses as a rule do not want to trample people but standing someone in front of an 1,100 pound animal to stop it, is not at all safe.