Call the oral surgeon (or dentist) who did the extractions. He might have a dry socket, but he will need an examination in order to determine that. When I had four teeth extracted my oral surgeon did follow ups at no charge. Tell the oral surgeon he is having a problem and ask if he will do a courtesy follow up.
Also, he needs to get the rest of the teeth out. Have you asked your oral surgeon if he will make a payment plan for you. If he will not do that find an oral surgeon who will. They can treat the pain and the infection but until they get rid of the SOURCE of the infection he will continue to have problems. DENTAL INFECTIONS ARE NOTHING TO FOOL AROUND WITH!!!! He has an infection in his mouth, do you realize how close that is to his brain. Please find someone who will make a payment plan and get the rest of those teeth out.