Is there any gadget to help with hay-fever?

Heyy, no there isn't really. An allergy is an allergy and not much you can do about it. I had hayfever when I was a kid to such an extent, that during spring i would just walk outside and my nose would start bleeding on some days. Best you can do is take allergy meds. Depends how old your son is...now im 21 and still have hayfever but its mild and your son should grow out of it during his teen years if he is still young. It is possible your son may be allergic to more then just hayfever. Try getting an allergy test done and seeing what else may be the problem. Good luck!