How Can Ankle Swelling With Pain, Itching And Cast Discomfort Be Treated?

hey, ive recently been put in a cast for a broken ankle and my cast is very heavy and rough on the delicate foot. it really hurts when i move and i cant sleep properly. i am 12 years old and this is really frustrating and discomforting. please tell me what i should do? (PS: My ankle is really swollen and there is hardly any space in there and my leg itches really badly)