Feeling crap after drinking beer is often nothing to do with alcohol – obviously within reason, but more likely to do with the chemicals and preservatives and all manner of artificial additives that they put into commercial mass produced beer and other alcoholic products.
Definitely this. Try some proper German beer as it’s brewed to the Reinheitsgebot (purity law) which means it can only be brewed with water, hops and barley (yeast wasn’t included for some reason). You’ll then find out if it’s the alcohol content or not.