Children who are being bullied are more than twice as likely to have psychosomatic [physical complaints caused by stress] complaints compared to children who are not being bullied. This was reported in a study in Pediatrics by G. Gini, Ph.D. and T. Pozzoli, Ph.D. They did a meta-analysis of 30 studies involving more than 219,000 children who had psychosomatic symptoms. Some of the children had been bullied. The study determined that any repeated and/or unexplained somatic [physical] symptoms are a warning sign of the possibility that the child is being bullied. The somatic complaints can include: recurrent headaches. breathing problems, poor appetite, sleeping problems, etc.
So, if your child has somatic complaints with no reason for them besides stress [psychosomatic] then it is very important to check for bullying as one of the causes of the stress.