I vomit after just one drink of alcohol when before I had no problem drinking multiple drinks without feeling nauseous.

It is possible that you may have developed an intolerance to alcohol, which can be either long-term or temporary. If you find that you vomit after consuming alcohol, it may be a good idea to start with just one drink and see how your body reacts. If this has been happening consistently, it may be best to avoid alcohol altogether and explore other options. If you have any further questions or concerns, feel free to reach out to a healthcare professional for guidance.