he reaction started in my lips immediately after I ate the bread. I had been on Amox for 2.5 days w/ no reaction.
If the reaction started in your mouth right after you ate the bread, the bread is the most likely culprit. Antibiotic reactions typically include hives (or some other kind of skin rash) and in severe cases difficulty breathing, but it's unlikely that an antibiotic reaction would start on your lips.
If you need to be on an antibiotic for your tooth they should be able to switch you to something from a different class of antibiotics until you get this sorted out.