At 6:30pm central time in the USA I saw a rapidly twinkling red blue and white star in the sky. It was about south east and I was really confused. I looked it up it might be Sirius but I'm not sure. I know it's not an airplane cause it hasn't moved in 20 minutes. Does anyone know?
Sirius is the most likely identification. It is visible in the South East at 6:30 from the USA, it is the brightest star in the sky and it's brightness makes the twinkles caused by the atmosphere more noticable. Similarly its brightness makes the colours caused by twinkles more apparent.
By shaking the tripod a picture of the apparent colours of Sirius can be captured https://epod.usra.edu/blog/2012/01/sirius-twinkling.html
There are several other bright stars in that region of the sky: Betelgeuse, Rigel and Procyon, any of which could have been your star, but Sirius is the most likely simply as it is the brightest. The stars will be back in (almost) the same positions tonight. If you can find Orion and Orion's belt, and follow the direction down you will get to Sirius, which should confirm your identification.