Red rash on face

My wife has developed a red rash on her face about six months ago.  Her dermatologist told her that he doesn't think it rosacea because it doesn't flare up but doesn't say what else it could be.  We really need to figure out what is causing this.  She does take quite a few medications and she does seem to have allergies.  The rash also appears around her ears.  She also says that her neck itches but I can't see any rash there.  Please help.  

[Dr_Aparna]

Hi,
This could be allergic manifestations to the drugs, maybe or it could be due to any other stimuli in her environment since she has a tendency toward developing it.
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)
•Pollens and plants (nettles, poison ivy, poison oak, and so on)
•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.
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.
Typically, chronic hives go away on their own, whether you treat them or not.
REF:http://www.myonlinewellness.com/topic/hivestreatment