My 6yr old nephew has recently become very sensitive. For example things that he loved a couple of months ago for like Harry Potter and Doctor Who really scare him. He's always been squeemish about falling over and blood but he's started to become almost phobic at the sight of blood. Blood relating to falling over ifyswim he only watches pg things !
I am experiencing similar with my own DS aged 6. And I have an ancient child development book (1960s / 1970s) which tells me this is a normal stage of development.
It says that confidence falls a little and that its a time for developing stutters (as was 2 yrs old) - that its a time of flux now until about 10 when you very much get a sense of the child as they'll be when they're an adult (the other side of puberty).