A Couple Of Weeks Ago I Started On The Ideal

A couple of weeks ago I started on the Ideal Protein diet. At the end of day 3, I developed hives from the top of my head to the top of my feet. None on the bottom of my feet. It was a Saturday night so I tried home remedies like Benedryl oral and topical until I could see a doctor on Monday. He prescribed steroid cream but I got no relief so I went back Tuesday and he prescribed oral steroids which helped but caused some pretty severe side effects like panic attacks and phobias etc. I am scheduled to see an allergist next month but I am not sure this was an allergic reaction. I have heard of a ketogenic rash. Is that a real thing and would an allergist be helpful?