13 year old peeing his pants

Im just going to get right to the point.  My step son is peeing his pants only at school.  He is in 7th grade. We had him medically evaluated and no problems were found.  He had a bed wetting problem and hasnt wet his bed in 6 months but now that school has started he wets himself at school.  Should we get a second opinion from another doctor?  What can we do as parents to resolve this issue?  

[babygirl6152]

what did the child say?
Is he mentally challenged or emotionally disturbed?
Give us some more to go on here