extreme headaches?

i will get a serious migraine after one drink, i also get extremely flush and red in the face after 1-2 drinks of alcohol. I am not dehydrated as i drink a ton of water throughout the day. I also tend to have all day hangovers with terrible headaches and nausea (this is when i get drunk). Is there a reason for this? someone said i could be allergic to alcohol? my poison is silver tequila and sprite. Any way to keep this from happening so i can enjoy a drink or two with friends without coming home and needing to immediately go lay down?