I have a very painful, itchy rash. it is on my stomach, legs, arms and knees. it started in november and is still going on. the worst is my stomach. i?

Chronic rash: Some persistent conditions that can give such a rash are psoriasis, eczema, contact dermatitis, scabies, and a medication reaction. Psoriasis usually gives well-defined red, scaly patches, often symmetrical over elbows, knees. Eczema has poorly-defined, red, fissured patches, often about creases of arms, wrists, behind knees. A dermatologist can diagnose the problem, and give appropriate treatment