J.M.
More than likely the red, swollen gums are from NOT brushing as well as he should, in other words poor oral hygeine. This is not a true emergency but he does need to be seen in the next few days. There may be something else going on. In the meantime, have him run his soft bristled toothbrush under HOT water to soften it even more and brush very gently, angling the bristles toward the gums. It will be tender, and they will likely bleed. Also have him rinse with warm salt water with some hydrogen peroxide mixed in. The peroxide is a very good disinfectant. Whatever he does, do not let him avoid brushing he needs to get the plaque off of his teeth and keep them clean. We always told parents that their kids with poor oral hygeine needed to stand a little closer to their toothbrush. Don't use mouthwash. The alcohol in it may sting.