The flashing was to indicate that the system was operating in a manner that is damaging to the catalytic converter
Probably a rich running condition.
It could also be an ignition problem. Do not drive it as is, you will melt the cat converter down . If you have to drive it, go to autozone and have them read the codes and drive it home, and post what they tell you.
Maybe we can help you figure it out. just remember , if the light is flashing, it is telling you that the catalytic converter will be damaged if driving continues.If that happens, pull over and let it cool down for 10-15 minutes and continue. Dont put off getting it fixed, it will likely snowball into something real big.
Keep your cool, get the codes, post them here. We will all be here.