Why am I getting easily winded all of a sudden?

Due to being overwheled with work and trips, I have not been able to run in two weeks. Before those two week I could run several miles without getting winded. For the past week I get winded from doing things that aren'teven strenuous. Running to the car to get something will even exhaust me. I tried running again a few times; now I can't even complete a mile without problems. What is going on here; did get out of shape that quickly? Am I sick, because I sure don't feel sick.