It depends on what religion you practice. If you're Christian, place a cross and a statue of the Virgin Mary in his room. If you're Wiccan, a pentagram would be appropriate, along with images of the healing Buddha and Quan Yin. If you're neither of these, then the ancient symbol of healing, the caduceous, would be appropriate along with an image of the greek goddess Hygeia.
As for your son, you might want to think about finding some affordable Reiki classes, which could help ease some of your son's pain and anxiety. Please let me know if you would be okay with me adding both of you to my healing book so I may send you Reiki.