My Grandson Is 3 Soon-to-be 4 In May. He Has

my grandson is 3 soon-to-be 4 in May. He has run high fevers for the past 2 days of 103.5 off and on. My daughter-in-law took him to the doctor and she said it was Cat Scratch Fever, but there was no bite, her cat does not have claws, no blisters. His lymph nodes in his throat or swollen and near his groin area. My concern is mono, or brucellosis as his mother is an FFA teacher and they are around livestock a lot. They put him on antibiotics but I wanted your thoughts on the situation