2 year old DS has always been an amazing sleeper. Slept through the night from 4 months old. Then suddenly (since about a month) started to wake up multiple times a night requesting a drink and refusing to go to bed in his own bed screaming the house down. He used to sleep by 8 pm the latest but now refusing to sleep until 11 pm, requesting his toys, books, wanting to run around the room etc. He only takes one nap in the nursery 12-2 pm. Any help would be appreciated, I feel zonked.