bumps, rash? uknown

a week a ago i started to get tiny little red bumps on my legs, arms, body and thigh. it'll just pop one here and it'll disapear in 24 hour it feels like something bit me. but lately i been  getting them on my inner thigh tiny red bumps around  a big rash.  they're irriating and itchy sometimes.  I don't know what it is? what do you think?

[Dr_Aparna]

Hi,
It seems to be an allergic rash.When an irritant comes into contact with your body, your immune system sends chemicals, including histamine, to fight it. The sudden spike in histamine levels can cause an outbreak of hives in the upper layers of the skin. Hives are often caused by a hypersensitivity to:
•Foods (commonly eggs, shellfish, nuts, berries, dyes, or other additives)
•Drugs (any drug can touch off an allergic reaction, although allergies to penicillin, sulfa, and aspirin are especially common)
•Pollens and plants (nettles, poison ivy, poison oak, and so on)
•Animal fur
•Insect bites or stings
•Exposure to heat, cold, or sunshine .Other potential triggers include physical exertion or exercise, stress, illness, chemicals, cosmetics, textiles, and pressure from materials rubbing against the skin.
Comfort is the main goal of treatment, since most hive outbreaks are relatively minor and short-lived. To soothe itchy skin, try cold compresses, calamine lotion, a cool shower, or a tepid bath with a few tablespoons of cornstarch (the kind sold in drugstores) thrown in. Try an over-the-counter antihistamine to reduce your body's response to the irritant and to relieve pain.
ref:http://www.myonlinewellness.com/topic/hivestreatment#s22
The important thing is to try and find out what is causing it and then avoiding it.