Ice, Relax dude. You're probably just pregnant. Your hormones will try to protect the fetus and turn your stomach against the alcohol. Mrs. Colreone went through the same thing. You should probably notice the symptoms disappear when you finally stop nursing, somewhere between 9months and 1 year.

All kidding aside, it could be a bunch of things. You've said that you've quit for a week or so. That'd be enough time for any acute (immediate) stomach damage but not chronic (long-term) or any issues with your liver.

You may have something else all together, and your liver is telling you "Look, I can deal with the disease, or I can deal with the booze. Not both. Take a break".

You may also be slightly allegric to certain types of alcohol (well, actually, the other things in there, which is why it's different types...). Not much you can do about this. Allergies are funny. People assume that because they haven't had issues in the past, they're not allergic. Typically, it takes several exposures to start getting a good allergic reaction going, and they intensify with each exposure.

Finally, let's bring in the world's experts. Now many nations claim to have advanced drinking prowess, but as somebody who's travelled widely, and drank heavily, I can tell you there truly is one group that towers over all others in terms of raw ability to put down mind-numbing quanities of alcohol and not feel any affects..... So, Kagemusha, Watchman... what do you advise?