My ds is 3 1/2 and has been a wonderful sleeper for most of his life. He is the kind of kid that we will go up change and then read and he will just stay in bed looking at books until he falls asleep. He also is still napping for 2 to 3 hours in the afternoon. Lately, he is pitching a fit when it is time to go to bed. He will go up and then go through the routine, but then will stall and stall. After that doesn't work, he will start crying or sit in the hallway and scream. If we come up he will be fine for a few minutes and then repeat the process once we leave. Eventually he will wake up his sister who will start crying

I am thinking he is losing his nap. I let him stay up yesterday during nap time and then he fell asleep on the couch waiting for dinner. Is there anyway to make this transition easier?