Took about a week after the trip to start feeling the effects.  Luckily that just happen to be the week I went to EFY.  I spent a ton of time going back to my dorm and using the bathroom.  I had to take a shower after every use.  It was awful!

I'll point out what someone else mentioned above...I never went to a doctor so this is self-diagnosed.  I had never had that kind of sickness and haven't ever had it since.  If it wasn't giardia I don't want to ever experience giardia...I assume it could have only been worse.