Why does alcohol make me feel sick?

Just wondering what to do here. I (18f) have been drinking for years now since the age of abt 13. Not a heavy drinker or a regular drinker but ill happily have a few at a social gathering. Recently though alcohol has been making me feel really nauseated, and I don’t mean excessive amounts either, literally by the end of drink two ill be feeling really sick. Not remotely drunk, just nausea. I’m not a heavyweight by any means but I can hold my drink reasonably well and have been able to drink many times that and not feel sick at all. This has only been happening for the last month and I’ve tried some strategies like eating beforehand, drinking different types of alcohol, drinking slower and none of its worked. does anyone have any advice on how to not feel really sick when drinking?