Hangoverandover

I am just a curious bystander with a big headache but I only had two beers. This is the second time it has happened. I'm in South Vietnam and I mentioned it to a friend and he said that it must be the formaldehyde. Pardon me for stringing out this rumor but it really made me consider whether or not I'll be having any more beer for quite a while. So what other factors could be at play here and I'll rule out eating excessive sweets for you and will also add that I am of good health.