I am almost done going through a tube of Crest Pro Health toothpaste and I am noticing something horrible: my teeth are worse off now than they were to begin with! Upon further investigation, I realize my teeth have been discolored by the stannous Fluoride that the toothpaste contains. This really pisses me off because now my teeth have started to go downhill after using WHITENING toothpaste for a month. Anyone know what I can do?