The mental training rollercoaster

Ok- even though you took 2 days off, you might need a little more time.  Even though it was a mini sprint, if you pushed yourself hard enough you still might need a little more recovery time.  Taking it easy for a week isn't all that bad of a thing.  Remember that your muscle need rest in order to recover and get stronger.  And...after starting back up after a race, make sure to ease into it by doing some easier workouts in the beginning.  Don't expect to PR on a run and defintiely avoid track workouts or tempo runs.  Do a few recovery workouts until you know you're ready to jump back into it.

Also something to remember- not all your workouts are going to be awesome.  They might be awesome, good, ok, kinda bad, or REALLY bad.  Sometimes there's a reason behind it, other times you just can't figure it out.  Don't let one bad workout spoil your mental game.  Just suck it up and start fresh the next day.  Remember that one bad workout doesn't dictate every workout.

And to answer your question- yes, we all have some really bad workouts so no need to worry

And congrats on completing your fist tri!

Did you train for post-race letdown?  Nope.  It's one of the few things you can't prepare for.  All you can do is roll with it and know that you will bounce back.  It's standard, and the bigger the race (not necessarily longer, but the more important to  you) the bigger the post race lag can be.  It's like being sick.  Even though you feel like crap, just know that soon things will be back to normal. 

This is a good time to go buy yourself something tri-related.  That usually helps.