I know it's hurting you so much just for the mere fact that he's hurting. I would take this opportunity to teach a life lesson. This is something that happens, regardless of age or setting. And it is a great opportunity to teach him a lesson about life and friends.
I have gone through this with my son and told him I know it's hurting his feelings. I know he really liked his friend and that it's not very nice that they won't play with him. But we can't force people to play with us. Sometimes, they just don't want to and we can find new friends to play with. No, he didn't like the idea, at first. But I told him there are other kids that need friends, too, and maybe he and they could play together and become friends. That way, he'd have more friends to play with. Then, maybe the other kids would want to play later. He did find others to play with finally. :) And he was fine with the other kids not wanting to play.
I don't know if it's just him, but maybe just let him know that we can have lots of friends, and that he can maybe learn some new games and have fun with new friends. He can even teach them some games that he knows. Kids like to teach/learn new things; so, this might help his desire grow.
But keep the long-term perspective in mind. No matter who we are or how old we are, we ALL have to deal with this at some time: a new school, new day care, new town, new neighborhood, new job, etc. So, just take advantage of the opportunity to show him how to meet new people and that it's okay and fun to make new friends.
Best wishes, and I hope you're both feeling better soon!