Patience is the important thing here. Take it easy and slowly, loosing a little bit of fitness is far more preferable than seriously hurting yourself,
"If there are signs or symptoms of systemic involvement (e.g. pyrexia, fatigue, muscle aches, swollen lymph glands, etc.) as in 'flu or symptoms of a 'chest' infection (hacking cough, 'dirty' phlegm, pyrexia, etc.) then 2 weeks post illness should be allowed before resuming intensive training to avoid relapse and / or potential life threatening complications such as cardiomyopathy or endocarditis
Remember that these common diseases (colds, 'flu, chest infections, etc.) are all potentially serious and life threatening. Don't ignore the symptoms. If in doubt, leave it out - don't train."
Ric