Hi.. Thanks for the query.. As the diagnosis is clear that you have developed poison ivy rash along with hives ad welts... Redness, soreness and itching is an outcome of allergic reaction only.. First of all start taking anti histamines like Benadryl or Levocetrizine to reduce redness and itching.. Continue with another course of Prednisolone but only after consulting your Physician.. Do cool compresses over the rashes.. Apply a steroid ointment like Triamcinolone Acetonide to reduce inflammation, swelling and redness.. If there is pain anti inflammatory painkillers like Ibuprofen can relieve.. Avoid scratching it to avoid infection. If there is still no improvement consult an Emergency room and get evaluated.. Hope this helps. Regards.