eczema vs fungus (ringworm)

My son had an unusuall rash that broke out on his bottom, started as dry patches. Then grew larger and became more distinct, raised red rings. I believed it to be ringworm. So started treating it like such for 6 days. The rash had spread across most of his buttock by this time. His treatment was interupted when he went to his fathers house, for 6 days. When he came back, it was worse and I started treatment all over again. I have now seen a few dry patches that were not present before develop on his upper arm and on the side of his leg. How can one be sure that it is eczema and not ringworm or another fungus??
-Vivica

[Dr_Aparna]

Hi,
You cannot be sure of what it is exactly unless it is seen by a doctor and diagnosed correctly.
Some-times even we don't get it right becuse the lesions in all the conditions can appear similar.
The only way to identify it is to note the response to treatment.
You could try corticosteroid application on the affected area.This will help in eczema.
Also anti-histamines can reduce itching associated with eczema.
Ringworm, also known as Tinea, is a contagious fungal infection of the skin.The best known sign of ringworm in people is the appearance of one or more red raised itchy patches with defined edges.
Topical antifungal drugs containing miconazole and clotrimazole, available by prescription or over the counter, are used to clear up the infection. Fungal infections can take weeks or months to clear up.
Terbinafine is highly effective for Tinea corporis. It treats itching, burning, cracking, and scaling that accompany this condition.
ref:http://www.medic8.com/healthguide/articles/tinea.html