Suggest Treatment For Hives

I have been having hives for three days now. They are patchy but symetrical (like they'll be on either side of my neck, on both arms, on both shins, etc). I have been prescribed 5 days worth of Prednisone, and have been taking Zyrtec and Benadryl as well. About three hours after taking the medication the hives fade or go away complete, but show up again in the morning. I have not eaten any new foods, have not switched shampoos or laudrey detergents and have not taken any new medication. I do not have a fever or any other symptoms of illness. The only other oddity is that I just got my period, but my last one ended just 13 days ago. What's going on?