Why does my car shimmy/shake when I apply my breaks

What is your question?

My 2009 charger 2.7 When slowing down or coming to a stop My car shakes ,I feels as if something on the under side is loose . And my tires are hard 'almost like thier stiff or something ' Is this from the same issue or two separate issues. How do i go about fixing them both

What makes this problem better or worse?

Road conditions,stopping,