I injured my back and had to take off 6 days training my cage fight is now 1 week away.?

should i be resting or tryin to 'get back into really amazing cardio shape' i havent lost that much fitness but i dont feel superhuman like i was before i urt my back. im worried if i start doin really intense cardio sessions i will get sick due to overtrainin or doin too much after taking a week off with injury. and i have been coughin up yellow phlegm should i keep trainin or get rid of it first?