What Could Chronic Itch All Over The Body Indicate?

Im 41 female. i have itching all over my body except for my head, private area and feet. i have tried hydrocortisone creams, anti itch creams, been taking benadryl every night for 2 weeks and im still itching...this has been going on for 2 months now...can you tell me what it is and how can i treat it?