The rash on your 7 year old's forearm responded to an excellent "naturopathic" remedy for several, or should I say, for many medical problems. One of the "main-stays" for dermatological diagnosis is that "the doctor needs "to see" the "lesion," that is, the rash, "before" it is treated" to make the diagnosis, usually. Sometime the patient gives the clinician the diagnosis by what they report in the medical history. For example, in this case, the patient may report "I saw a brown spider crawling up my arm before I noticed the rash." Insect or spider bites are just one cause of rashes. There are many causes. This is the why a dermatologist is such a valuable person when it comes to diagnosing and treating skin conditions.
The above having been said, I am glad that your son's rash is responding to your remedy. We are thanking that your salve worked.