Why does alcoholic root beer destroy me?

For reference, I drink very regularly – at least 3 drinks a day basically every day. Everything from beer (up to 10% abv), spirits, mixed drinks, sweet liquors, etc and i have a very high tolerance. Nothing much effects me. I usually don’t even feel buzzed after a few beers unless they were specialty beers with like 9% abv.

Recently tried this stuff called “not your fathers root beer” which is a root beer with about 5% abv. Immediately after drinking 1 beer I felt sluggish and exhausted, like my blood was full of thick oil, and my throat/chest felt almost like it was backed up. Not quite sure how to explain it. I chalked it up to just eating/drinking too much food.

Next day, I have another one of these and I get hit with the same effect again right after. I have to lie down for about 20 min then i’m feeling ok.

Since there’s no ingredients on the label i have no idea what’s in it but im curious if anyone has any ideas what might be causing this.

Is it just coincidence? could it be something to do with high sugar content combined with alcohol? Could it be whatever root is in root beer? Or did they just put some extra toxic waste in this?