Hard Bump on Cat's nose

I recently adopted a kitten to be companion to my 4-year old cat. She had a little patch of ringworm on her ear which has been treated, but still infected the adult cat. Now the big cat has a bald patch over his eye that has been seen by a vet and diagnosed (via blacklight) as ringworm. The cat was given an injection of antibiotics as a precaution, and because of the proximity to the eye, the vet told me to use Lotrimin instead of a more runny medicine that she usually prescribes. After a week, the ringworm patch has not worsened;however, the cat now has a hard bump on the bridge of his nose. It is about the size of a pencil eraser and is extremely close to the ringworm patch. He still has his fur in the area and it does not seem to be sore for him. Is this an allergic reaction to the Lotrimin? Or was he misdiagnosed?