Help with severe itching

I itch and scratch and have red rash all over.  What could this be?
Could it be an allergic reaction to something? The only new thing I can think of
is a new medication I started?  Any answers will be greatly appreciated.
I can't stop itching it and this only makes it worse. Thanks.

[Dr_Aparna]

Hi,
This could be an allergic reaction called hives which can be caused by medications.Hives are red, itchy welts or swellings on the skin that often come in clusters.
Hives can appear anywhere on the body, cropping up either in one small area or covering large patches of skin. They most often occur as part of an allergic reaction. No one lesion lasts more than 24 hours, but new ones may continue to appear until the condition resolves.

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).

Hives that have a sudden onset and spread quickly after you've taken a medication mean that you've probably developed an allergy to that drug. Stop taking it and call your doctor for advice immediately. If it's clear that the medication is the cause, your doctor will most likely want you to replace it with another.

Hives usually appear suddenly and go away on their own in a matter of days, hours, or even minutes. Chronic hives, however, can last for six weeks or more.

To soothe itchy skin, try cold compresses, calamine lotion or  a cool shower. You can use oral anti-histamines like Cetrizine to combat the itchy feeling and to treat the rash.

ref:http://www.myonlinewellness.com/topic/hivestreatment