...hard to walk. What could it be? After picking up the little guy from school today, he complained of his upper back hurting (between shoulder blades) and says he felt tired and is hard for him to walk. I asked him if something happened at school, if he got hurt and he said no. I also checked for any marks or bruising on his back and there were none. Once we got home, I continued to observe him and he seems ok, his energy's up and was playful. I asked him again if his back was still hurting when I put him down to bed tonight and he said yes. Not sure what this is all about...definitely calling his doctor first thing in the morning. Just checked on him a few minutes ago and he's sleeping comfortably and peacefully.