What could be wrong with me?

I have this weird rash it isn't all over my body or located in one spot either. They are like random patches of skin that are dry and itchy. I have one on my leg, on on my arm, another on my knee and several on my buttox. I have also been losing weight unusually. I have been really hungry lately and seem to be a bottomless pit! I eat more than usual and have been really fatigued so I know that it is odd to be losing weight. I have lost almost 20 pounds and I just sit around and eat. What could possibly be causing the rash, fatigue, and hunger?