Blacked out for the first ever time.

I am 21 and have been drinking for at least 4 years. I have always had a high alcohol tolerance being able to drink a lot without much effect. I have never had a hangover, even if I went out the night prior. If anything alcohol helps me sleep a restful night and wake feeling good.

Last night I went to my local pub with some friends and drank a usual amount. I had a few glasses of wine and a few pints of beer – probably 7-9 drinks in total. I have 1000% drank more before on different occasions, but this time it destroyed me. I have no memory of last night at all. I was told I threw up nonstop, had a fever and was passed out nearly all night.

How can I have drunk so much over the years and felt nothing/mild tipsy-ness and then all of a sudden be so drunk that I can’t walk and lose my memory. It’s very strange to me. Any advice is much welcomed