What whitening for teeth doesn't burn?

I recently purchased Crest Pro Effect Whitening Strips, and after two days the roof of my mouth was cracked, and my entire tongue feels like a severe burn. When I drink or eat anything acidic it now burns like crazy. No sensitivity on my teeth though... I'm looking for something else that won't make my mouth feel like it's on fire afterwords. Pretty disappointed though, bought the toothpaste too :/
--------------------
the success of teeth whitening products vary from person to person. i didnt see results with the strips, and with mouthtrays i usually got all the gel on my gums. the whitening pen worked for me using it a cpl of tiems a day
Source