What Causes Swelling And Redness In Elbows, Chills, Fever And Sweats?

My husband has elbow redness swelling chills fever and sweats. He went to the doctor and they gave him 2 shots of antibiotics in the buttox and he is taking 2 different antibiotics orally to treat cellulitis which the doctor said it was. He went for a follow up to see if it had spread and see if it was getting better and the doctor is now concerned that it may not even be cellulitis and he may send him to the ER if it doesnt start clearing up by tomorrow. My husband has no insurance and we are avoiding it at all costs but we definately want to treat this even if thats our only option. Could this be serious and do you know of anything else this might be???