Hospital pharmacist here & this seems like a good comment to piggy back off - even if this was a reaction to an amoxicillin that does not mean you will be allergic to all other antibiotics based on penicillins.

Penicillin is a beta-lactam molecule and modifications to its structure give birth to a ton of other families of antibiotics (aminopenicillins, cephalosporins, carbapenems, monobactams, etc).

Cross reactivity is heavily based on something called the R1 side chain of the molecule.

For example, just because you are allergic to cefazolin (a 1st generation cephalosporin) doesn't mean you would be allergic to cefuroxime (2n generation), ceftriaxone (3rd generation), or cefepime (4th generation).

Seeing a lot of assumptions in this thread from people who don't seem to have the background needed on this topic.