Need help with weird headaches

Hello guys I dont drink very often ,

sometimes I might drink almost a full 70cl vodka or whiskey or cognac in a 10 hours span and end up fine , almost no hangover

But some other times I just drink 2 or 3 beers and get a very serious headache after , that might last 6 hours….

I dont understand why, at least I know its not something to do with quantity

I always make sure to hydrate properly and eat properly, just sometimes I get these surprise headaches out of nowhere and its only when drinking…

I really enjoy alcohol, I never have any bad whiskey reaction, Im always happy and fun to be around , I have no reason to stop drinking except these fkn surprise headaches…

Does Somebody have an advice for me ? Thanks