Ringworm is a common infection caused by the tinea fungus that you can pick up from other people and from dogs and cats. The infection is called ringworm because of its appearance: a pinkish red rash that spreads in a circle (or ring) around a center of normal looking skin. The edge of the circle is raised and looks something like a worm under the skin.
Ringworm is typically treated with over-the-counter antifungal skin creams, powders, or liquids and usually clears up in about four weeks. Although the infection generally doesn't cause serious problems, people with weakened immune systems may have some trouble getting rid of it. That might be the problem in your son's case. I suggest that you take your son to his pediatrician for a diagnosis of the bumps on his head and the blisters on his neck and eyelid. If this is a stubborn case of ringworm, treatment with a prescription fungicidal cream or if necessary an oral antifungal agent should clear it up. If your son has developed a bacterial infection secondary to ringworm (from scratching), the pediatrician can prescribe an antibiotic.
I also recommend giving your son a multivitamin plus a supplement of GLA (gamma-linolenic acid) in the form of black currant oil or evening primrose oil. GLA often improves skin conditions. The correct dosage for children is 250 mg twice a day.
In addition, you can use topical calendula cream or lotion made from petals of the ornamental "pot marigold" (Calendula officinalis) to soothe the affected areas of your son's skin. Look for products with at least 10 percent extract of this plant, and you might also try washing the irritated skin with a diluted solution of calendula tincture.
Andrew Weil, M.D.