Can't help with the injury, I'm afraid,
BUT my dad's grumpy mare had three months box rest after an op on her hind leg. We invested in an equine massage every two weeks, it honestly helped to relax her, and her muscles. She isn't a big carrot fan either- apples are anoter thing. We bought likits- no interest. So we chopped up carrot and poked them through haynets, or on the ground so she had to find them. At first we used haynets, however, so she wasn't moving around in the box so much and harm herself.
Also, try small holes in a net. It works for some, didn't for Josie- she just left the hay till we got a bigger holed hay net!