Medical notes say i'm allergic to augmentin (amoxicillin and clavulanate) but me or parents can't remember what happened. is it worth trying it again? what might happen?

Not worth it: Most Augmentin (amoxicillin and clavulanate) allergies are due to antibiotics given for ear infections at a young age. Generally speaking you do not "grow out" of allergies. There are plenty of alternatives to this medication so no use risking a severe reaction.

Penicillin testing: A commercial skin test for penicillin call pre-pen is available specifically for this reason. Even true penicillin allergy resolves in 50% of individuals after 10 years of avoidance and 75% of people after 15 years of avoidance. With a questionable or unknown past reaction penicillin skin testing can accurately determine whether penicillin can be given or not.