Having plodded on (stupidly and stubbornly) through the obvious onset of a nasty chest infection for nearly two weeks, I finally decided to stop running during the first week of December as I felt I wasn't allowing my body time to recover. The doctor confirmed a chest infection and some antibiotics helped to kickstart the recovery.
It felt weird not to run for nearly two weeks. Lots of little muscle twinges and a feeling of being heavy and bloated, but once I got used to it, I could feel the benefit to my body. To anyone else wondering about whether to run with a chesty cough or not, my advice (and I'm not a qualified (or even an unqualaified!) doctor) is to give it some time to clear up. I have run with head colds before and actually felt better, but once it's on your chest it's time to get healthy before running again. Respect your bodies people!! (unlike me, but I'm an idiot).
ANYWAY, back into it again tonight. I was dreading it as the first run after some time off is always mighty depressing. But actually it was ok. I felt healthy and although a bit sluggish, reasonably fit. A little heavy and my hips ache a little tonight, but otherwise not as bad as feared.