A sore throat could be caused by an infection called streptococcal (strep throat). It spreads mainly through coughs and sneezes, but your child can also get it by touching a toy that an infected child has played with. In addition to difficulty swallowing, symptoms of streptococcus in children can also include headaches, nausea, stomach pain and vomiting. Do not delay in seeking medical assistance if you see these symptoms of streptococcus infection in your child.