I have had poison ivy, all lesions healed and gone, then a itching and flaming red skin started on hands and feet, legs, butt, not external.

Different cause: You're itching at this point is probably not related to the poison ivy.You should see a medical doctor since there can be internal causes of pruritus better known as itching.

Dr Hodge and another doctor agreed

Repeat contact: The most likely cause is continuing contact with the poison ivy resin left on your clothing, shoes, car seats etc. You need to wash them all out with a laundry detergent. A less likely cause is a secondary bacterial infection from scratching the areas.