When my little mare was on box rest after major colic surgery we hung various objects from the ceiling of her stable for her to nibble at- These objects used to include;

sweads, carrots, apples, home made horsy treats, likits, a lickit boredom buster and a horse ball was also hung from the ceiling. She thought they were very inseresting and it kept her occupied- if your horse even gets bored of that, I would recomend another method-

An object a day- pick an interesting object (e.g a football, dressing gown or book) and place it in the horse's stable (as long as it doesn't spook them!) and let the horse investigate it and find out what it is

Sorry for the huge comment lol x

My horse has a nutball and she Loves it! seriously, she can kick and roll it around for hours :L

 Hi! For horses with laminitis you should always keep control of their weight, so you shouldn't give them anything except what the vet recomends. It may not be the ideal thing, but you have some powdered supplements to keep them calm. 

Either way, always consult with your vet. He's the best person to help you. 

Hope your horse gets better soon