Ate you asking if cancer could cause the reactive lymph nodes? Possibly, but you did the right thing and have been to the doctor and they are attempting to see what is going on. That you were put on an antibiotic, they seem to feel you have a treatable infection. What was the ultrasound of? and you have an infected bite? Yes, that infection could cause our immune system to jump in and lymph nodes can react as yours have. But you are smart to make sure. Anyway, let us know what the ent says