Dermatology Questions? Ask an Online Dermatologist.
And when did you take these medications ?
And when did you take the Cortizone shot and if you know how much (this question is the most important)
It is most likely an allergic reaction, but contact dermatitis is also possible, both should respond to cortisone, the most important medication you took. It will definitely take more than a day to see a response and if you do not notice some improvement 24 hours after the cortisone shot, you need to be reevaluated. You will then most likely need an oral steroid taper. I would continue to take the Benadryl for now, or to avoid drowsiness, Claritin (OTC).
Let me know if you need any more clarification. If this answers your question, please complete the rating above. It's how we get credit for our service. You may still email me with questions, after the rating. Best wishes