Save me Jeebus!

In the lead up to my first five k event I've been attending the free training sessions offered by the awesome people at Suunto and Run Melbourne. They ran for twelve weeks, and I ran in the beginners group, which mostly has been a really uplifting and positive experience. I run much faster and further in a group than I possibly could on my own, and the advice from more experienced runners has been invaluable.
I did, however, miss the last two session...one due to nagging shin splints that refused to heal, then I caught a nasty cold that left me coughing up goobers for a fortnight and missed another.
This is very very bad, as the beginner group increased their distance slightly each week, and so by missing two sessions (and bitching out slightly at a previous session due to the aforementioned shin splints) I was quite behind, distance-wise.
Last night was the last session, and I knew it was going to be hard for me, but Oh Jeeeeeeeeeeesuuuuuus I had no idea! We did just over five.....in the rain....and I was coughing.....dear Lord, we ran up a hill just so we could run down it again, which is insane! The rain washed all my sweat into my eyes, my lungs were just burning and I had to stop several times because I thought my heart would escape my chest. I threw a small tantrum in the last two hundred metres or so and ran screaming up the hill. So I didn't make the whole distance, but still, it was the longest, hardest run I've ever been on. Afterwards I stood with my hands on my knees, heaving from the pit of my belly, and would have blown some serious chunks if there had been any food left in me. Harsh.
So after a lot of trying not to die, a stretch, debrief, and a serious pigout on chips from Lord of the Fries, it was off home. I thought I felt a little better until I realised that I'd driven home with only my parking lights on :/
Soooooooooooooooooooo, what went wrong? Well, for one thing, probably not enough food pre-run. I didn't like my lunch (even though I made it myself, haha) and I hate to eat just for the sake of eating, or because it's time to eat. Also maybe a little stressed out, though I am not sure how that factors in. And at the source of it all, I just wasn't quite good for the distance.
So, half a tube of Deep Heat later, I'm a little stiff but otherwise ok. Fortunately, the nature of exercise that's so intense is that we forget how bad it was...right?