What Causes Itchy And Inflamed Skin On The Joints Neck And Feet?

Hello, my 22 month old son has had a skin problem for some time, mainly inflamed, itchy, red patch on his joints, neck and tops of his feet. I have taken him to various doctors, and been given many different creams, including steroid creams none of which seem to have much effect. Also I have noticed he has really bad halitosis. I am wondering if it is possible he has some kind of bacterial infection.