I agree with Christin, doubt its detox. To add to what she has already stated, it could also be nerves. Nerve bumps are very itchy. Usually spread out not in an isolated area. I get them from 2 things, stress, or sunshine. When I go out in the sun in the spring for the first time i develop small itchy bumps. Among the other possible causes are the "natural" soaps, and switching to them. An allergy can develop at any time in your life. By your saying you switched soaps, I would think that is the culprit. Other possible causes are foods. Most of the most "allergic foods" are strawberries, dairy, nuts, peanuts, shell fish, tomatoes, and gluten. Keeping a food diary can be very helpful. The problem is that the reaction can be delayed, meaning it doesnt happen right away. Have you eaten anything different? Or even alot of one food can cause a problem, alot of times the foods we crave we are actually allergic, or at least sensitive too. If the problem doesn't resolve, seek the help of an allergy doctor. They can test you for sensitivities, that way you will know what to avoid. The first line of defense is usually a steriod, a low dose of prednisone is the usual course of action.
Hydra-cortisone cream can be purchased over the counter, aloe can be very soothing, as well as healing to the skin. Can be purchased over the counter, or brake the leaf of the plant, and rub the gel on the irritated areas, providing that your not allergic to aloe.
For other recommendations for skin health, ive written an article about skin health, and recommendations.
Hope it helps. It can be very frustrating.