I woke up this night at 2:22am and I strted feel my throat hurst, and started coughing.
But still I’m not sure if it really was the cold, or I failed…
You shouldn’t worry too much. Being tense can lead to be distracted, so the only real thing that prevented you from LD’ing was your worry. Next time, just go with what happens, I’ve read of people having LD’s with any kind of illness, just because they didn’t care 
and also, there’s probably no cough in your dreams, and that’s the place where it matters.