I had a similar problem when I had forgotten which antibiotic I had been reactive to many years previously. I phoned my GP surgery and explained the problem and the receptionist checked and told me. I was stood in the dentist in great pain getting a prescription for an infection at the time so I needed the info then and there, I think if circs had been different she might have asked me to go to the surgery to be sure it was me, but of course if necessary the dentist could have vouched for me. I know that there are formal ways to get your info but a quick and easy way to start might be at your GP if they are the helpful kind.