For whatever it is worth from a distance...it is a lot for a kid to worry if they need surgery they will die. It is a lot for a kid to feel like it is hard to trust adult teachers because they believe they will be teased. It is a lot for a kid to fear doing any physical task in front of other people. It is a lot for a kid not to trust their own body. Any one of those things would for our family constitute reason to get help from a therapist. It is admirable if a kid finds some ways to cope on their own, but when the worry is persistent like this (whether they are vocalizing it or not) I believe some outside help is appropriate.