It sounds like your son is having a physical stress reaction to his worry about papers and school. There are effective techniques for helping kids deal with this kind of stress. It is not uncommon as the academic requirements get more demanding.

You might want to contact the teacher and guidance counselor. You can ask for a meeting to alert them to your son's distress. You might be able to find out if his stress carries over into school, if they have seen these reactions, if they have done anything to help, or if they are even aware of what is going on.

See if they can help.  If you are not satisfied, you can try a professional social worker or family counselor. Talk to them first and find out if they are versed in stress management and if they work with kids.

Good luck. You are wise to be aware of your son's stress, and you can do something to help him.
Bette J. Freedson, LICSW, LCSW, CGP
Clinical Social Worker
JustAsk Expert
http://www.singlemomsos.com/index.html