Can I Use Antibiotics For Rashes And Scabies?

my husband has a rash that started as a small patch lower back and I put antibotic cream and it moved to middle back. Went to the doctor and prescriped Permithan and used two weeks in a row but still very itchy and now on his neck and upper legs. Dr diagnosed scabies but not going away. He is also very tired and had a bad cold before it started. Is there a disease that starts with a rash like this? 47 year old healthy male UPS driver