Since this seems to be a reoccurring theme in your son's life right now it's certainly worth looking further into. Did he give a reason for why he drew the pictures at school? Were there other boys involved, or did he do it on his own? Did he explain who the crying character was suppose to represent? Be sure to ask your son if this was a self portrait. If he says yes, ask him what he was sad or upset about. There may be something going on in his life that's making him sad, which caused him to wet the bed. It could also simply be something he saw on t.v., or something he was peer pressured into doing at school. Try not to sound too alarmed when you speak to him about it. Kids can often sense fear or anxiety. Simply ask him why he did that and what he meant by it in a conversational voicetone.
 
It may be beneficial for him to speak to the school counselor as well to see if he gives them the same story he gives you. He may also be more willing to talk to someone else because he is afraid he might get in trouble with you or his father.
 
Try to get additional information from your son, and give things some time. If his behavior continues, consider taking him to a child psychologist to decipher what your son is trying to communicate to you through his drawings and bed wetting.
 
Boys Town National Hotline
1-800-448-3000