Worried About Kieran

I am so worried about Kieran. I know he's been having troubles at school. He keeps begging me to write him a note saying he can stay in from recess. . .I ask him why and he tells me he has a cold and shouldn't be outside. I know he feels fine because he comes home and plays with his sisters and Nick all the time without any word about not feeling well.
I wonder what's going on. Is he the cause of some problem and he doesn't want to be around other kids. Or, are they just being cruel to him for some unknown reason...? I know he's a sensitive kid and he cries at a lot of things but I don't know if he's that way at school. He did say something to the effect that he was called a "baby." I can feel his pain with that. I was a cry baby and it caused me a lot of problems when I was in grade school. I remember feeling alone and like I didn't have any friends. It was horrible. I would never do grade school again-never. It was one of the worst experiences of my life. I think that's sad that my childhood memories are riddled with bad school experiences. I should have loved being at school...I remember loving to learn but actually socializing...no chance at that...
I hope he's not experiencing those same feelings but I honestly fear he is. I wish I could be there at school as a fly on the wall. I want to take it all away and give him nothing but great memories of grade school. I didn't ever have any problems making friends when I was in Jr. High and High School so maybe he can make it through this year and the next and find peace and friendship when he's in Jr. High.
I truly worry about suicidal thoughts though. He's threatened to "kill himself" in the past and you can never know how serious that really is. I would hate to lose my child because I didn't head his warnings. I just hope the pressure doesn't eat him so much that he feels there is no other way. I am so worried.
I have thoughts of him being upset because it's Christmastime and he only lost his dad a year and half ago so the pain is still really raw. But, I can't just pin his problems on that without at least trying to help him see that it's what his family, who loves him unconditionally, thinks. I remind him all the time that he's loved and I make sure I take him with me whenever I leave to go somewhere so that we get that one on one time and so that he feels special.
All I can do at this point is listen to the Lord and give Him all these problems. I know He'll see us through but sometimes it's hard to keep faith. I wouldn't say my faith is wavering, it's just that sometimes I forget to have faith. I forget to let God have my fears and troubles. He did say that he'd never leave us.