Try not changing the feed too much as your horse my colic again, when you are riding why dont you try the kick click flick method. put your leg on, if your horse has abit of a delayed reaction put your leg on again but this time click with your voice, if you need to do as before but when you click flick her with the stick then apply a firm leg aid and as soon as your horse is walking fowards and your happy reduce pressure but as as she backs off again click and flick!