Hey! I agree with Victoria, call your farrier, he'll know what is the best treatment.
I once had a horse that had a serious problem with a quarter crack, the shoe and the work he was under putted to much pressure on the hoof! The farrier changed his shoe and stiched his hoof but it was month of recovery!
I recomend not working him too much while he has the crack!
Hope it helps and that your horse recovers super fast!
You should contact your farrier to see what the appropriate measure would be to treat them. Because quarter cracks can get worse if not treated right away you should try to limit riding as much as possible. However, if the farrier says it should be fine, then it should be fine. Another thing, is to try to figure out how the quarter cracks occurred. It could be by the way your farrier trims your horses feet or if the hooves are too dry. If they’re dry u can just use some hoof oil.