petewyse:
I used to stay up wayyyy passed my bedtime every night, like 4am-5am, writing and playing video games. Then wake up fresh as a daisy after 4 hours sleep! Now, well... if I stay up passed 2am I feel exactly like you're describing for a whole day. Getting old does suck!
vincentvega:
Did these loud places have smoke inside?  Just being around smoke will give me a hangover.  Also, the loud noise can affect your inner ear equilibrium, causing feelings similar to motion sickness.
vincentvega:
Now that I read the post below about the allergies. Your hangover is probably caused by your allergies and Benadryl.  Benadryl will make you feel drunk when you wake up.  Get a shot of Celestone and some Flonase.  You'll feel so much better, you'll probably want to send me a 25-year single malt as a thank you gift...and I will accept.
sanitariumlxix:
What @vincentvega said is most likely. The only other thing I can think of is if you upped dosage on, or started new meds. I experienced those exact symptoms when I went on Celexa.
oddly_charming:
What the guys above said. Also possible mild food poisoning.
trills:
I used to feel like that sometimes after a late night out when I was t-total. Less than fresh venues, passive smoke, junk in crappy soft drinks if you touch 'em etc etc. So weird.
sid:
Have you been sleeping too much?  I know that sometimes I feel like that way when I sleep more than I should have because of my meds.  Like there are days where I feel my brain just hits a brick wall, and I can't function.  I wish I could give you a solution to it. If you hear a good one, please pass it along to me if you could!
kiley:
You know that's really strange because I felt like that yesterday. I think it had something to do with being in a new place and there being a ton of anxiety involved. I was anxiety hungover. :/