Have you tried using hydrocortisone cream 1%? I would try it. When we first moved to KS, I was here not even 1 day and I woke up with little bumps on the backs of my hands, which itched, and became somewhat pink/red. My hands became dry and cracked with the bumps and after about a week - 2 weeks it went away. It was a reaction to something, but not a bite of anykind. There was not heat or bite marks, no fever, and I was pregnant. About 6 months after I had this my husband also got it, but his was in patches on his fingers and hands. He is a hunter and I thought it was from a poison bush/tree he was exposed to, but when I had it, I touched no trees or bushes. Benadryl, an antihistamine - which slows the histamine response to swelling, itching, and redness, and hydrocortisone, a steroid, relieves itchiness, redness, swelling, and skin irritations, are the two most common creams. Most irritations of the skin respond well to these creams. I couldn't tell you what caused them, but question your kids to see what each of them did before they came on, and find a common denominator. It could be as weird as cosmetics, lotions, soap, or environmental allergens. Good luck.