Question: what to do if you think you have poison ivy?
Answer: Apply an over-the-counter corticosteroid cream for the first few days.
Apply calamine lotion.
Take oral antihistamines, such as diphenhydramine (Benadryl, others), which may also help you sleep better.
Soak in a cool-water bath containing an oatmeal-based bath product (Aveeno).