Help - Tank dying

Hi, my tank was overrun with flatworms (the red planaria) I got the Exit stuff but for a week siphoned thousands of them. Treated my tank. They died...did a 40% water change..tank still reeks. All bristle worms and bristle stars as welll as all of my fish died. My coral is dying. Did ANOTHER water change..the coral is NOT all dead yet (changed carbon filter (will change again tomrrow)....tank is still cloudy....still smells bad (not as bad as before). Should I just give up????? Can the coral recover???