I have a 5 year old son and for the past year or so i've notice him taking on some anxiety traits. If he thinks of something that is uncomfortable to him or frightens him he gets physically sick. The first time i noticed it i thought he was sick and took him to the ER! He will vomit, says he feels sick, and get the shakes until he eventually goes to sleep.
He also (within the last year and a half) started to walk around the couch talking to himself. If he can't, he will start crying and gets angry/frustrated.
He also has problems with speech articulation, if that makes any difference.
He's my oldest child, so i don't know if this is all normal or not. I have anxiety and so does my mother, so i don't know if he is showing early signs, or if this is common in all 5yo.