itchy rash help!!!!

My son has a rash all over his body except face it is very itchy and the spots are small red one's. I have also the same problem but my spots are mainly on my legs and are so itchy.
We have been to the doctor and he said they looked like chicken pox but we have already had them so he said it must be scabbies and we were given some cream twice which has not helped.
I have looked up scabies and yes we have itchy rash but we dont have the lines (burrows) and the spots don't seem to look the same as on photo's. There is only me and my son that has this in our household and if it was scabies surely other members who we have close contact with would have them too.
I don't think it is scabies has anyone having same problems or any ideas on what the problem could be.
Many thanks Sam xx

[Dr_Aparna]

Hi,
These look  more like allergic bumps and they seem to co-relate with the fact that they are itchy, as you have mentioned in your post.

Chicken pox lesons usually develop fluid-filled blisters on the red rash, if this is absent in your case then this may not be it. The chicken pox lesions (blisters) start as a two to four millimeter red papule which develops an irregular outline (a rose petal). A thin-walled, clear vesicle (dew drop) develops on top of the area of redness. This "dew drop on a rose petal" lesion is very characteristic for chickenpox. After about 8 to 12 hours the fluid in the vesicle gets cloudy and the vesicle breaks leaving a crust.
ref:http://en.wikipedia.org/wiki/Chicken_pox

The pathological reaction that takes place on your skin due to foreign particles is considered as allergy rash.
This rash can be identified by itchy and swollen red bumps or patches all over the body. Certain foods, medications, cosmetics, insect bites, animal dander, plants, exposure to sunlight are some of the common causes that trigger this reaction.

Some of the rashes subside gradually without any medications. You can take anti-histamines for the itching, like Cetrizine/Loratidine. Also, you could apply Calamine or Pramoxine lotion on the affected areas to soothe the itch.

ref:http://www.allergyasthmazone.com/allergy/factors-that-can-contribute-to-allergy-rash/