<human>: Reddit, I went out to see my friend's band last night.  Though I didn't drink that much, I was pretty hammered when I got home and threw up for the first time since I was seven.  

I know that right now everyone is thinking "whatever, lightweight," but I normally drink way more than that without consequences.  My roommate says I must have gotten some "bad liquor."  I've heard that expression before, but I'm not really sure what it means.  

I'm also trying to figure out why last night was so different for me.  I know that I gave blood about a week ago and I was on my period last night, too.  Could that be the real explanation?

Could you distill the essence of the text into 1-3 sentences?
<bot>: Why is it that I went from being able to handle 10+ drinks with no problem to 4 drinks and I'm gone?