I keep getting bad breath?!

I Brush my teeth two times a day along with Listerine and flossing. I tried a new tooth past its the 3D tooth paste made for whitening teeth? I brush my tounge and the top of my mouth but still it smells. Bad. I have had many cavities and one root canal. Do I possibly have tooth decay? Or is it just my toothpaste?

Oh and I did try a different tooth paste but it only helped a little and this just started recently like about a week ago.