Hi,
It could be a case of hives.Hives are an itchy skin rash -- red, raised bumps with a paler center - triggered by an irritant. They can appear anywhere on the body and can vary in size.
Hives, also known as urticaria or wheals, can pop up in one area, fade, and appear in a totally different place within a matter of hours. An episode of hives can be over in a few hours, but most take about 48 hours to completely disappear. Some stubborn cases may even last a few weeks.
Common triggers include food allergies, drugs, viruses, insect bites and stings, plants, exercise, heat, and cold. In most cases the cause will remain un-identifiable.
Some children are simply more susceptible to certain irritants than others. Their immune systems reacts more quickly -- sometimes even to substances that are usually harmless -- and attack what appears to be an invader. When this occurs, the immune system releases a chemical called histamine to combat the irritants. Histamine makes blood vessels in the skin leaky, and the fluid that escapes gets trapped in the lower level of the skin, causing the bumpy hives.
You can use cool compresses or a cool bath to reduce irritation and itching, but since hives are a reaction to histamine, antihistamines like Benadryl (diphenhydramine) are usually the most effective treatment.
Antihistamines make most children a little drowsy. Avoid the irritant, if you know what it is.
ref:http://www.myonlinewellness.com/topic/hiveschild
No new suntan lotion, right? No new fabric against his back right? I ask about the fabric because my daughter got similar rash inbetween her legs and her allergist figured it out .. it was from formeldahyde in the fabric to keep the fabric stiff! Once she washed it 8-10 times it was gone and the garment was great to wear.
Benadryl usually helps my dd when she gets weird rashes like that. Today she is 17 and is anaphylactic to latex, plums, nuts ..
I'm not a Dr or medical professional, just a mom like you.
Good luck,
Cheryl