Beer hangovers

I drink a lot, usually wine or liquor, and I used to pride myself on never really getting hangovers. But I’ve been dating this guy who is really into beer, so I’ve been having more pints lately than I ever have before, and I wake up, even after like 3 pints, with a horrible headache. Why is this?? If I had 3 Jameson’s or 3 glasses of wine I’d be totally fine in the morning!