Alcohol intolerance/allergy? Help?

Hi all, basically in short I used to be able to get drunk at a fairly normal level, but nowadays I can drink tons and tons and not even feel tipsy in the slightest. I start to feel really sick as well. Keep in mind I don’t drink often anymore so I don’t think it’s a tolerance issue. I’ve experimented with eating before drinking as well; not eating then drinking as well as eating then drinking, but it doesn’t change the outcome. Nothing happens. Could this be a developed intolerance/allergy to alcohol? Please help