Training after flu.....

Hi, I'm after abit of advice, help etc, Over Christmas I picked up the flu bug like alot of people I guess, I was really rough, couldn't swallow, and when I did felt like razor blades were going down my thoat, no energy, muscles ached, really bad cough..you get the picture Had it for about a week, now two weeks later I feel quite abit better apart from a slight cough and whizing a little bit, I been for two runs now, only 3 miles and not two fast, but the times are really really bad, worse as if I hadn't run for about two years, I don't feel to bad when I'm running I'm just really slow, now I don't know if I have gone back to early, or if its something else, I expect the times to not be great but when I've been injuryed in the past and been out for ages, the times weren't as bad, Has this happened to anyone else, any advice or help would be much appreciated