回复:四岁的孩子昨天下午回来叫右腿疼,问过老师在学校里也没有摔过,现在走路都疼,约了
my son had the similar problem last year. It was caused by cold virus, and it is not unusuall. It will recover in a couple of days. Check if your son had other cold symptems, if so, it's likely caused by cold virus.