Thanks for the advice - will try the Epsom Salts. My daughter has been riding her for 3 weeks and she's been perfectly OK so it's a bit of a change of character all of a sudden coinciding with the electric fence being erected.
Hopefully she'll calm down a bit - thanks again.
We've had our pony for 3 weeks now and she's in a fenced off field with a gelding who she gets on with very well. There is another gelding in the adjacent field that she loves to try to take a chunk out of. We've bought some electric fencing to try to prevent them getting too near to each...