Feeling sick after 5k

Hi all, I usually lurk at this board and I was hoping you knowledgeable folks could help me out.

I ran my third 5k today (woohoo!) and set a PR of 35:49 (double woohoo!).  Ran the whole thing, had a sip of water at mile 1.  Weather was pleasant, mid-70's, a little sun but then overcast.  I have felt terrible since the race this morning!  I had a banana beforehand as well as a sugar-free sports drink.  After, I had a banana, a couple orange slices, another sports drink, a gel, another couple bottles of water.  I've eaten regularly since.  I'm so tired and almost nauseous and (TMI) I've been peeing like crazy. 

Up until about three weeks ago, I'd been running 3 times per week (~9 mi/wk) and had a "long" run of 3-4 miles.  I got sick with a nasty head cold (allergy related) and had been working my mileage back up.  Today's race was my longest effort since the illness.  I'm guessing the sick feeling could be a holdover from that?

I have another 5k next weekend and I don't relish the thought of feeling this way again afterwards.  Any thoughts on what I can do?

I signed up for my first half-marathon today, too... it's at the end of October.  I'm excited, but I'm also wondering what the heck I'm doing to myself, ha ha!

I would run the 5K next weekend.  I really doubt that its the running that has you feeling badly.  It is possible that the stuff you ate and drank contributed too it.  For me, there are particular water brands that dont agree with me.  Poland Spring and Nestle are two that come to mind.  I have not heard abou****er affecting anyone else but its something to be aware of.  Again, try again next week and see what happens.