Just a cold?

Around August 20th I came down with what I believe was a cold. I went ahead and did a sprint on the 23rd, even thought I still felt sick. The swim was okay, the bike not too bad, but the run was horrible. I took the following week pretty much off while I shook of the cold, then started with some easy swims and some easy biking.

Recently I went out for an easy run. Nothing hard, HR around 145, 11:30 pace or so. I got 1.5 miles in and it was somebody hit me with a shovel. I got light headed, nasueated, legs rubbery, etc. I felt if I kept running I would literally pass out on the ground. A few days later I tried it again and  the same thing happened.

What's going on? I was running 7.5 miles before I got sick. Did I lose it all in 2 weeks? Am I still sick? Anyone had a similar experience? Did I just wait too long to get back on my runs?

I hate to think I have to start all over, but I just don't seem to have a decent run in me. I have been advised to go out and do some Z1 biking and I am going to do that, but when will I get my lungs back?

I don't log workouts here, but FYI I have done 2 5ks, 1 10k, and 2 sprints this summer, so I have been getting off the couch.

Brent