My Son Is 11 And He Is Getting Over Hand,

My son is 11 and he is getting over hand, foot mouth disease. He is about 3 weeks out since we had it diagnosed. I came home today and his penis in engorged. He has never been circumcised and has never had an issue as far as disease or irritations. His diet has not changed nor is there any significant pain, just swelling. It does look painful, to me his mother....