Hi my only adive is if you are not happy with what is happeneing, change the nursery if you can. the manager should be happy to sit down and discuss any problems and best course of action and your son should have a key worker who is there to help your son whilst he is there. Is your sons key worker helping, him playing with him, working with him to play with others?
I changed my daughters nursery and i feel very happy where she is now x