4 year old suddenly hates daycare?

My 4 year old son has been going to the same daycare since he was 15 months old. I have loved the teachers/caretakers there from the get go. They have a pre-school program Wed-Friday for the 2.5-4 year olds. My daughter is 1.5 years old and also attends the same daycare. Both go part-time but she only goes on Wed and Friday, whereas my son goes Wed, Thurs, and Friday for the preschool program. Anyway, over the past month or so, my son has become increasingly upset about going to daycare. He says he wants to stay home with us, and doesn't like daycare. I asked him why, and he has no real answer, which was to be expected as he is only 4. The providers there are the same people who have always been there, so I don't have any reason to believe that they're treating him poorly. Also my daughter loves these people as well. My son will be starting Kindergarten next year, so I don't want this to continue escalating, as he will be in a full day/week kindergarten. What can I do? How do I figure out what is causing the sudden aversion? There are a few new children around his age, and I've speculated that maybe they're not very nice to him, but I also don't believe that is the case. I'm at a loss of what to do.. via /r/Parenting http://ift.tt/2yGvemd