I have been blacking out every time I drink, even if I don’t consume large amounts of alcohol.

For the past two or so months I have been blacking out nearly every time I drink, regardless of the amount of alcohol I consume. I am not a frequent drinker, I drink once a week on average. I used to be able to drink 9/10 drinks a night and have great memory of everything that occurred the next day. Now, I can have as little as 2 or 3 drinks and have large gaps of memory, and if I drink more I black out. What might be happening?