I would recomend calm and condition i think its dodson and horrel that make it. I wouldnt, personally, reccomend magic calmer. It made my horse goo nutters! But he is very similar to how you described yours :P. :)

I tried magic on my mare and it had no effect and have heard others say the same but thats not to say its like that with everyone.  I just think brewers yeast is a good one to use and you have nothing to loose at the price of 3.49 for 900g  www.naturalhorsesupplies.co.uk this is the link to the website I use its a fast service to.

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