What could be causing hives?I starting getting hives yesterday and took a Benadryl at night, hives returned this afternoon.Nothing that I have eaten has changed.I'm not allergic to anything that I know of I started using Colgate whitening Pen 3 days ago these are the ingredients Dimethicone , Paraffinum Liquidum , PVP , Trimethylsiloxysilicate/Dimethiconol Crosspolymer , Hydrogen Peroxide,Polyethylene,Flavor,Sodium Saccharin