Describing feelings is very difficult for a 5-year-old. Actually, it is difficult for most of us, no matter how old we are. I would try to handle it in a very matter-of-fact way. “It’s time to get ready for school now, and you have to go whether you want to or not.” Check with his teacher to find out whether he is resistant or unhappy once he gets there. If so, schedule an appointment with her and see whether the two of you can get to the bottom of the difficulty. Your inability to volunteer may have been very important, or it may be merely a coincidence.
Just before going to sleep is a time when many children will talk about things that bother them. At tuck-in time, say something like, “When I was a little girl I sometimes didn’t want to go to school because a girl there said she didn’t like me. Did something like that ever happen to you?” Don’t push too much or sound too eager. He will probably work through whatever it is that is bothering him in time. Unless he shows other problems, I don't see any need for a therapist.
Our parenting advice is given as suggestions only. We recommend you also consult your healthcare provider, and urge you to contact them immediately if your question is urgent or about a medical condition.