Any tips, I have a 4 y/o that has been broken about 8 weeks now, all going well then suddenly started getting really stuffy (it's a mare if that helps at all!) teeth, saddle and back all checked, we have been doing mainly hacking so I don't see any reason for her to have got sour in the school, but she has all of a sudden decided to just not go when I put my leg on, ignores the whip, eventually after a lot of work and the help of someone with a lunge whip on the floor we do get somewhere but it's not great. She isn't like it out hacking. Any tips? She's also been kicking out when asked to go forward again only in the school.