I am at a loss as to what to say/ do.
He has been upset at nursery and I have just seen it for myself. (Not all the time by any means, but it only seems to happen to him in the group). Somethimes they all play really nicely together, other times they just don't want to know him (they are friends outside of nursery, he normally only sees them there.
We were at a picnic this afternoon with 2 of his friends. They were playing nicely , then the other 2 decided they didn't want him to be with them any mroe. The started saying xxx smells and running off. Everytime he went over they did the same. The parents didn't seem to bother until ds yelled 'shut up!' to them - then then came over all concerned at my son's behaviour! 
How would you approach this. I have tried to give his various strategies, but he says he wants to play with them and that is that. I would love any ideas. I also don't know how to talk to other children when the parents are there (and are not doing anything) - if I say something, I feel like the child 'telling tales' on their children, yet I feel that I am letting ds down with a rubbish approach.